1. 1. Summary

Linux native and containerized install actions now use `<output-base>-mongo-shared-install`, derived from Bazel's active output base. This keeps the shared install tree on the same filesystem as the output base — native Linux actions publish through cheap hardlinks (containerized actions see EXDEV across the container's separate mounts and fall back to stable symlinks or copies, as before) — and avoids dependence on volatile `/tmp`.

Updated `install_rules.py`, `fsutil.py`, Linux container action configuration, wrapper cleanup, and focused tests/documentation. macOS behavior remains unchanged.

1. 1. Safety and compatibility

• Explicit `MONGO_BAZEL_SHARED_INSTALL_DIR` overrides are honored consistently by the install script, post-build publication, and container configuration; cleanup only removes derived paths, never caller-owned overrides.
• The legacy temp-based Linux tree is removed during clean and output-base generation migration.
• Linux clean removes the derived sibling tree and the last published root (so cleans still take effect when the output-base key drifts, for example when TEST_TMPDIR changes). Clean invocations route through the direct integration, which owns that removal.

1. 1. Testing

• `bazel run format`
• `bazel test //bazel/install_rules:install_rules_script_test //bazel/wrapper_hook:cross_linux_test //bazel/wrapper_hook:cleanup_test`

All focused tests passed.