chore(migrations): Consolidate migrations

[devsjc]

Consolidates all migrations into one file for ease of reading.

[github-actions]

Benchmark Results

Benchmark results

?   	github.com/openclimatefix/data-platform/cmd	[no test files]
?   	github.com/openclimatefix/data-platform/internal/gen/ocf/dp	[no test files]
?   	github.com/openclimatefix/data-platform/internal/interceptors	[no test files]
PASS
ok  	github.com/openclimatefix/data-platform/internal/server/dummy	0.005s
{"level":"debug","time":"2026-08-18T19:25:16Z","message":"Completed migrations"}
goos: linux
goarch: amd64
pkg: github.com/openclimatefix/data-platform/internal/server/postgres
cpu: AMD EPYC 7763 64-Core Processor                
BenchmarkPostgresClient/small/GetForecastAsTimeseries-4         	     132	   8291569 ns/op
BenchmarkPostgresClient/small/GetForecastAtTimestamp-4          	     312	   3682720 ns/op
BenchmarkPostgresClient/small/GetObservationsAsTimeseries-4     	     924	   1243356 ns/op
BenchmarkPostgresClient/small/CreateForecast-4                  	     334	   3331049 ns/op
BenchmarkPostgresClient/small/StreamForecastData-4              	      27	  42783411 ns/op
PASS
ok  	github.com/openclimatefix/data-platform/internal/server/postgres	35.156s
?   	github.com/openclimatefix/data-platform/internal/server/postgres/gen	[no test files]

Benchmark vs base branch

goos: linux
goarch: amd64
pkg: github.com/openclimatefix/data-platform/internal/server/postgres
cpu: AMD EPYC 7763 64-Core Processor                
                                                   │ bench-main.txt │    bench-devsjc-prepare-1.0.0.txt    │
                                                   │     sec/op     │    sec/op     vs base                │
PostgresClient/small/GetForecastAsTimeseries-4         8.398m ± ∞ ¹   8.292m ± ∞ ¹       ~ (p=1.000 n=1) ²
PostgresClient/small/GetForecastAtTimestamp-4          3.764m ± ∞ ¹   3.683m ± ∞ ¹       ~ (p=1.000 n=1) ²
PostgresClient/small/GetObservationsAsTimeseries-4     1.289m ± ∞ ¹   1.243m ± ∞ ¹       ~ (p=1.000 n=1) ²
PostgresClient/small/CreateForecast-4                  3.452m ± ∞ ¹   3.331m ± ∞ ¹       ~ (p=1.000 n=1) ²
PostgresClient/small/StreamForecastData-4              44.40m ± ∞ ¹   42.78m ± ∞ ¹       ~ (p=1.000 n=1) ²
geomean                                                5.743m         5.580m        -2.83%
¹ need >= 6 samples for confidence interval at level 0.95
² need >= 4 samples to detect a difference at alpha level 0.05