ci: optimized github actions caching and workflows

- Updated GitHub Actions workflows and custom actions to optimize caching strategies and runners.
- Configured separate restore and save steps for bun store caching with non-PR restrictions.
- Added darwin release bazel cache seeding and fallback keys for cache restore.
- Removed native-inputs workflow action and disabled PR-side Rust validation.

.github/actionlint.yaml

@@ -0,0 +1,6 @@
+# actionlint only knows GitHub-hosted labels; register the self-hosted ARC
+# runner scale set (infra/docs/04-arc-and-caching.md) so `runs-on: omp-kata`
+# lints clean.
+self-hosted-runner:
+   labels:
+      - omp-kata