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

[CraftSpider]

Is there a particular reason ARM doesn't run tests? If any are failing, that may be a sign things need fixed.

[dakehero]

The current ARM64 entry is a cross-build on an x64 runner, so the e2e tests cannot simply run without an emulation layer. Would you prefer that I keep this cross-build-only job or should I add a separate windows-11-arm job for native ARM64 Windows build and test coverage?

[CraftSpider]

Hm. I think it's fine this way, no strong opinion either way for now.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 29.54%. Comparing base (cafcb17) to head (5ff8f00).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1370      +/-   ##
==========================================
- Coverage   29.54%   29.54%   -0.01%     
==========================================
  Files         273      273              
  Lines      180506   180506              
  Branches   180506   180506              
==========================================
- Hits        53328    53327       -1     
  Misses      55476    55476              
- Partials    71702    71703       +1     

Components	Coverage Δ
tectonic	51.40% <ø> (ø)
bridge_core	34.16% <ø> (ø)
bridge_flate	17.64% <ø> (ø)
bridge_fontconfig	96.17% <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	34.94% <ø> (ø)
cfg_support	94.84% <ø> (ø)
dep_support	0.00% <ø> (ø)
docmodel	84.61% <ø> (ø)
engine_bibtex	66.45% <ø> (ø)
engine_spx2html	0.00% <ø> (ø)
engine_xdvipdfmx	64.30% <ø> (ø)
engine_xetex	35.27% <ø> (ø)
errors	47.61% <ø> (ø)
geturl	28.20% <ø> (ø)
io_base	76.11% <ø> (ø)
pdf_io	14.19% <ø> (-0.01%)	⬇️
status_base	74.69% <ø> (ø)
xdv	55.28% <ø> (ø)
xetex_format	23.31% <ø> (ø)
xetex_layout	56.82% <ø> (ø)

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[CraftSpider]

Hm. I think it's fine this way, no strong opinion either way for now.

[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.