Add Windows ARM64 vcpkg target

[dakehero]

Summary

This adds vcpkg support for the aarch64-pc-windows-msvc Rust target by:

• adding an arm64-windows-static-release vcpkg triplet
• registering aarch64-pc-windows-msvc in package.metadata.vcpkg.target
• adding a Windows ARM64 vcpkg CI matrix entry

Verification

Verified on my fork with a targeted workflow that runs the same prep flow and packages the Windows ARM64 binary:

https://github.com/dakehero/tectonic/actions/runs/26043396816

The workflow completed:

• prep / main
• prep / rustfmt
• windows-arm64-vcpkg
• Install vcpkg dependencies
• Build and package

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 31.51%. Comparing base (ab5ef51) to head (6364a14).
⚠️ Report is 4 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1370      +/-   ##
==========================================
+ Coverage   29.85%   31.51%   +1.66%     
==========================================
  Files         273      275       +2     
  Lines      180530   180823     +293     
  Branches   180530   180823     +293     
==========================================
+ Hits        53889    56994    +3105     
+ Misses      54416    44722    -9694     
- Partials    72225    79107    +6882     

Components	Coverage Δ
tectonic	51.35% <ø> (ø)
bridge_core	36.90% <ø> (+2.65%)	⬆️
bridge_flate	38.82% <ø> (ø)
bridge_fontconfig	95.67% <ø> (ø)
bridge_freetype2	92.70% <ø> (ø)
bridge_graphite2	42.47% <ø> (ø)
bridge_harfbuzz	82.83% <ø> (ø)
bridge_icu	∅ <ø> (∅)
bridge_png	100.00% <ø> (ø)
bundles	40.84% <ø> (+4.76%)	⬆️
cfg_support	94.84% <ø> (ø)
dep_support	0.00% <ø> (ø)
docmodel	84.87% <ø> (ø)
engine_bibtex	67.46% <ø> (ø)
engine_spx2html	0.00% <ø> (ø)
engine_xdvipdfmx	64.30% <ø> (ø)
engine_xetex	35.73% <ø> (ø)
errors	47.61% <ø> (ø)
geturl	28.20% <ø> (ø)
io_base	76.11% <ø> (ø)
pdf_io	18.50% <ø> (+4.33%)	⬆️
status_base	81.92% <ø> (ø)
xdv	55.28% <ø> (ø)
xetex_format	23.31% <ø> (ø)
xetex_layout	59.57% <ø> (ø)

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[CraftSpider]

I think something is going wrong here, even the x86_64 vcpkg build didn't publish an artifact.

Edit: Unless that's related to the force-push you just made. I've re-approved CI

[dakehero]

Sorry for the back-and-forth here. I experimented with a native windows-11-arm pipeline, but there's a Cranko setup issue on the ARM64 runner, so I backed that out to keep this PR focused on the cross-build target.

[dakehero]

Switched the ARM64 job back to native windows-11-arm. Build, tests, and packaging all pass on my fork: https://github.com/dakehero/tectonic/actions/runs/30171333350

Could you approve the new CI run when you get a chance?

[CraftSpider]

Thank you for the time getting this working