Sequence windows after build job to avoid CI runner contention

Both jobs land on the same self-hosted runner. Run 129 segfaulted
odin test in build while windows was mid (uncached) SDK download/
splat at the same time; odin check passed and the test suite
reproduces fine in isolation, so this is resource contention from
running concurrently for the first time, not a code or toolchain bug.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

AGENTS.md

@@ -38,6 +38,7 @@ Commands (see `justfile`): `just run`, `just check`, `just test`, `just package
 6. **Windows builds are cross-compiled**: Odin can't link Windows binaries on Linux, so `just windows` builds objects with `-build-mode:obj` and links with `lld-link` against an xwin SDK. The VC runtime is linked statically; only Windows system DLLs are needed. New Odin core usage can need new import libs (e.g. `ole32.lib` for `os.user_data_dir`); the CI `windows` job catches this. Not yet tested on a real Windows machine.
 7. **Odin constant arrays can't be indexed at runtime**: lookup tables (`DECKS`, `LAYOUTS`, …) are `@(rodata)` globals instead of `::` constants.
 8. **Profile memory**: `profile` always allocates from the heap allocator, because the test runner frees each test's allocator afterwards.
+9. **CI jobs share one self-hosted runner**: `build` and `windows` in `gitea-build.yaml` land on the same machine. Running them concurrently once segfaulted `odin test` while `windows` was mid-SDK-download, so `windows` now runs with `needs: build` to avoid the contention.
 
 ## File Structure
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