Add no-legacy-computed rule to disallow computed and computed macros

[Copilot]

This adds an opt-in lint rule to prevent introducing legacy Ember computed APIs while teams migrate to tracked/getter-based patterns. It covers both computed from @ember/object and all macro imports from @ember/object/computed.

• New rule: ember/no-legacy-computed

  • Reports ImportSpecifier for computed imported from @ember/object
  • Reports all imports from @ember/object/computed (e.g. and, gt, sortBy, etc.)
  • Implemented as non-recommended (no default config changes)

• Rule docs

  • Added docs/rules/no-legacy-computed.md with scope, rationale, and correct/incorrect examples
  • Regenerated rule documentation metadata so the rule appears in the README rule table

• Rule tests

  • Added focused coverage for:
    • valid non-Ember imports and modern patterns
    • invalid direct and aliased computed imports
    • invalid single/multiple macro imports from @ember/object/computed
    • side-effect import from @ember/object/computed

// now flagged
import { computed } from '@ember/object';
import { and, gt, sortBy } from '@ember/object/computed';

[github-actions]

🏎️ Benchmark Comparison

	Benchmark	Control (p50)	Experiment (p50)	Δ
🟢	js small	14.39 ms	14.03 ms	-2.5%
⚪	js medium	6.93 ms	6.93 ms	-0.0%
🟢	js large	2.90 ms	2.80 ms	-3.3%
⚪	gjs small	1.25 ms	1.25 ms	-0.4%
⚪	gjs medium	622.30 µs	616.99 µs	-0.9%
⚪	gjs large	237.79 µs	239.48 µs	+0.7%
⚪	gts small	1.24 ms	1.24 ms	-0.0%
⚪	gts medium	619.76 µs	620.04 µs	+0.0%
⚪	gts large	237.79 µs	239.12 µs	+0.6%

🟢 faster · 🔴 slower · 🟠 slightly slower · ⚪ within 2%

Full mitata output

clk: ~3.35 GHz
cpu: Intel(R) Xeon(R) Platinum 8370C CPU @ 2.80GHz
runtime: node 24.16.0 (x64-linux)

benchmark                   avg (min … max) p75 / p99    (min … top 1%)
------------------------------------------- -------------------------------
js small (control)            17.08 ms/iter  17.74 ms  █▅                  
                      (12.10 ms … 30.43 ms)  30.19 ms ▆██ ▆ ▃              
                    (  5.62 mb …  10.20 mb)   7.34 mb ███▄███▄▁▁▁▄▁█▄▁▁▄▁▄▄

js small (experiment)         14.52 ms/iter  15.75 ms    █▅                
                      (12.16 ms … 19.17 ms)  18.65 ms ▃ ▃██ ▃▆   ▃         
                    (  6.81 mb …   8.24 mb)   6.93 mb █▁███▄██▄▄▄█▁██▄▄▄▁▁▄

                             ┌                                            ┐
                             ╷  ┌────────┬─┐                              ╷
          js small (control) ├──┤        │ ├──────────────────────────────┤
                             ╵  └────────┴─┘                              ╵
                             ╷ ┌───┬──┐      ╷
       js small (experiment) ├─┤   │  ├──────┤
                             ╵ └───┴──┘      ╵
                             └                                            ┘
                             12.10 ms           21.15 ms           30.19 ms

summary
  js small (experiment)
   1.18x faster than js small (control)

------------------------------------------- -------------------------------
js medium (control)            7.71 ms/iter   8.04 ms  █                   
                       (6.34 ms … 14.84 ms)  14.73 ms  █▂                  
                    (  3.45 mb …   4.15 mb)   3.56 mb ▇██▃▆▄▄▁▂▁▁▂▁▂▂▁▁▁▁▁▂

js medium (experiment)         7.45 ms/iter   7.70 ms   █                  
                       (6.20 ms … 13.44 ms)  12.94 ms  ▆█                  
                    (  2.59 mb …   4.47 mb)   3.56 mb ▇███▅▄▃▅▂▃▂▁▁▂▂▁▁▁▂▁▂

                             ┌                                            ┐
                              ╷ ┌────┬─┐                                  ╷
         js medium (control)  ├─┤    │ ├──────────────────────────────────┤
                              ╵ └────┴─┘                                  ╵
                             ╷  ┌───┬┐                           ╷
      js medium (experiment) ├──┤   │├───────────────────────────┤
                             ╵  └───┴┘                           ╵
                             └                                            ┘
                             6.20 ms           10.47 ms            14.73 ms

summary
  js medium (experiment)
   1.03x faster than js medium (control)

------------------------------------------- -------------------------------
js large (control)             3.54 ms/iter   3.69 ms  █                   
                        (2.60 ms … 9.77 ms)   8.44 ms ▂█                   
                    (  8.11 kb …   2.98 mb)   1.45 mb ██▄▃▄▃▂▂▂▂▁▂▃▁▁▂▂▁▁▁▁

js large (experiment)          3.13 ms/iter   2.93 ms  █▅                  
                        (2.51 ms … 8.16 ms)   6.10 ms  ██                  
                    (313.64 kb …   2.57 mb)   1.43 mb ▄██▃▂▂▃▂▂▁▂▂▂▂▁▂▂▂▁▁▁

                             ┌                                            ┐
                              ╷┌─────┬┐                                   ╷
          js large (control)  ├┤     │├───────────────────────────────────┤
                              ╵└─────┴┘                                   ╵
                             ╷ ┌──┬                     ╷
       js large (experiment) ├─┤  │─────────────────────┤
                             ╵ └──┴                     ╵
                             └                                            ┘
                             2.51 ms            5.47 ms             8.44 ms

summary
  js large (experiment)
   1.13x faster than js large (control)

------------------------------------------- -------------------------------
gjs small (control)            1.39 ms/iter   1.32 ms █                    
                        (1.17 ms … 6.89 ms)   6.16 ms █▂                   
                    (244.48 kb …   1.66 mb)   1.06 mb ██▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁

gjs small (experiment)         1.46 ms/iter   1.28 ms █                    
                        (1.16 ms … 7.00 ms)   5.98 ms █                    
                    (168.46 kb …   1.78 mb)   1.06 mb █▅▁▁▄▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁

                             ┌                                            ┐
                             ╷┌┬                                          ╷
         gjs small (control) ├┤│──────────────────────────────────────────┤
                             ╵└┴                                          ╵
                             ╷┌─┬                                       ╷
      gjs small (experiment) ├┤ │───────────────────────────────────────┤
                             ╵└─┴                                       ╵
                             └                                            ┘
                             1.16 ms            3.66 ms             6.16 ms

summary
  gjs small (control)
   1.05x faster than gjs small (experiment)

------------------------------------------- -------------------------------
gjs medium (control)         679.86 µs/iter 642.01 µs █                    
                      (568.88 µs … 6.38 ms)   3.67 ms █                    
                    (131.96 kb …   1.10 mb) 542.25 kb █▇▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁

gjs medium (experiment)      671.21 µs/iter 636.44 µs  █                   
                      (566.03 µs … 6.70 ms)   1.84 ms ▃█                   
                    (113.27 kb …   1.04 mb) 541.27 kb ██▄▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁

                             ┌                                            ┐
                             ┌─┬                                          ╷
        gjs medium (control) │ │──────────────────────────────────────────┤
                             └─┴                                          ╵
                             ┌─┬                ╷
     gjs medium (experiment) │ │────────────────┤
                             └─┴                ╵
                             └                                            ┘
                             566.03 µs           2.12 ms            3.67 ms

summary
  gjs medium (experiment)
   1.01x faster than gjs medium (control)

------------------------------------------- -------------------------------
gjs large (control)          266.11 µs/iter 257.19 µs  █▄                  
                      (225.58 µs … 6.08 ms) 331.24 µs  ██                  
                    ( 63.20 kb …   1.24 mb) 217.35 kb ▆███▆▇▆▅▄▅▄▃▂▂▁▁▁▁▁▁▁

gjs large (experiment)       277.63 µs/iter 266.43 µs  █                   
                      (224.43 µs … 6.40 ms) 444.21 µs ▆█                   
                    (133.56 kb … 965.82 kb) 216.65 kb ███▇▇▅▃▂▂▁▁▁▁▁▁▂▂▂▂▁▁

                             ┌                                            ┐
                             ╷ ┌──────┬            ╷
         gjs large (control) ├─┤      │────────────┤
                             ╵ └──────┴            ╵
                             ╷┌─────────┬                                 ╷
      gjs large (experiment) ├┤         │─────────────────────────────────┤
                             ╵└─────────┴                                 ╵
                             └                                            ┘
                             224.43 µs         334.32 µs          444.21 µs

summary
  gjs large (control)
   1.04x faster than gjs large (experiment)

------------------------------------------- -------------------------------
gts small (control)            1.35 ms/iter   1.27 ms █                    
                        (1.17 ms … 7.24 ms)   5.58 ms █                    
                    (216.52 kb …   1.91 mb)   1.06 mb █▆▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁

gts small (experiment)         1.35 ms/iter   1.28 ms █                    
                        (1.16 ms … 7.11 ms)   5.94 ms █                    
                    (415.04 kb …   1.72 mb)   1.05 mb ██▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁

                             ┌                                            ┐
                             ╷┌┬                                       ╷
         gts small (control) ├┤│───────────────────────────────────────┤
                             ╵└┴                                       ╵
                             ╷┌┬                                          ╷
      gts small (experiment) ├┤│──────────────────────────────────────────┤
                             ╵└┴                                          ╵
                             └                                            ┘
                             1.16 ms            3.55 ms             5.94 ms

summary
  gts small (control)
   1x faster than gts small (experiment)

------------------------------------------- -------------------------------
gts medium (control)         670.86 µs/iter 637.81 µs  █                   
                      (568.35 µs … 6.48 ms)   1.36 ms  █▇                  
                    (540.29 kb …   1.13 mb) 542.38 kb ▇██▄▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁

gts medium (experiment)      673.77 µs/iter 638.14 µs  █                   
                      (569.31 µs … 6.64 ms)   1.91 ms ▃█                   
                    (539.31 kb …   1.26 mb) 541.51 kb ██▃▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁

                             ┌                                            ┐
                             ╷┌─┬                       ╷
        gts medium (control) ├┤ │───────────────────────┤
                             ╵└─┴                       ╵
                             ╷┌──┬                                        ╷
     gts medium (experiment) ├┤  │────────────────────────────────────────┤
                             ╵└──┴                                        ╵
                             └                                            ┘
                             568.35 µs           1.24 ms            1.91 ms

summary
  gts medium (control)
   1x faster than gts medium (experiment)

------------------------------------------- -------------------------------
gts large (control)          265.17 µs/iter 259.53 µs  █▇                  
                      (224.66 µs … 5.69 ms) 324.51 µs  ██                  
                    (170.66 kb … 934.19 kb) 217.09 kb ▃███▆█▆▅▅▅▆▄▃▃▂▁▁▁▁▁▁

gts large (experiment)       264.24 µs/iter 257.42 µs  █▄▂                 
                      (225.67 µs … 5.95 ms) 315.42 µs  ███                 
                    (181.12 kb … 739.03 kb) 216.47 kb ▅████▇▇▅▅▅▆▆▄▃▂▂▁▁▁▁▁

                             ┌                                            ┐
                             ╷  ┌──────────────┬                          ╷
         gts large (control) ├──┤              │──────────────────────────┤
                             ╵  └──────────────┴                          ╵
                             ╷   ┌─────────────┬                      ╷
      gts large (experiment) ├───┤             │──────────────────────┤
                             ╵   └─────────────┴                      ╵
                             └                                            ┘
                             224.66 µs         274.58 µs          324.51 µs

summary
  gts large (experiment)
   1x faster than gts large (control)