## Why
Executor compatibility checks need a build identity that distinguishes commits
and compiler targets independently of the package release version.
## What changed
- Add optional `providerId` to exec-server environment metadata, cached at startup
and returned by initialization and `environment/info`.
- Derive the ID as SHA-256 of `git:<lowercase commit>:<target>`. It identifies a
standard build configuration, not exact executable bytes, and is omitted when
the commit stamp or target is unavailable or invalid.
- Embed the compiler target in `BuildInfo`, preserve compatibility with historical
metadata without a target, and stamp Cargo release builds with `STABLE_GIT_COMMIT`.
- Group Bazel build-script argument files under one `--arg-file` flag to reduce
Windows command-line length while preserving file order.
## Testing
Add deterministic build-ID vectors across targets, commit normalization and invalid
input coverage, and historical metadata compatibility tests. Extend exec-server
coverage for metadata caching and ensure runtime environment overrides cannot
replace the executor's build identity.
GitOrigin-RevId: 125a18c23de7ad006571940ba305836376c983f4
## What changed
- Add `codex-build-info` to resolve a packaged runtime's semantic version from `codex-package.json` while preserving the commit stamped into the executable.
- Represent source builds as version `0.0.0` and expose helpers for display, serialization, and source-build detection.
- Stamp `STABLE_GIT_COMMIT` into final Bazel Rust binaries so Git changes do not invalidate the shared library graph.
## Testing
- Cover packaged, source, legacy, and invalid-version resolution, plus serialization round trips.
GitOrigin-RevId: 669b02449644c738ba2946a1b7aafe4ec31a9edb
