Add Playwright Chromium RBE smoke target

[Jesssullivan]

Summary

• add a narrow //:playwright_chromium_smoke Bazel target for the GloriousFlywheel browser RBE proof lane
• launch Playwright with an explicit pinned Chromium runtime path instead of downloaded browser state
• skip Playwright/Puppeteer browser downloads in Bazel npm lifecycle hooks and document the proof boundary

Validation

• git diff --check
• npx --yes prettier --no-config --use-tabs --single-quote --trailing-comma all --print-width 120 --check scripts/run-playwright-chromium-bazel.mjs
• npx --yes @bazel/bazelisk test --config=ci --config=no-remote-cache //:playwright_chromium_smoke
• GloriousFlywheel REAPI proof: https://github.com/tinyland-inc/GloriousFlywheel/actions/runs/25776002138
  • target: //:playwright_chromium_smoke
  • command/config: bazel test --config=ci-cached
  • force execution: true
  • endpoint: grpc://gf-reapi-cell.gf-rbe.svc.cluster.local:8980
  • worker image digest: sha256:a567696e341f6eb0589ece9efd6014a2133a4f10831bdad31e8dd84055eff8a0
  • worker/platform: gf-reapi-cell-ff5f7699f-2td2v / gloriousflywheel-rbe-linux-x86_64
  • result: 2331 processes: 1477 internal, 855 remote; //:playwright_chromium_smoke PASSED in 1.3s
  • action evidence: external/bazel_tools/tools/test/test-setup.sh playwright_chromium_smoke_/playwright_chromium_smoke executed remotely with exit code 0

Note: local no-remote //:types_unit_tests currently fails resolving Svelte/Vitest config imports through the local Bazel runfiles shape. That target passed the prior GloriousFlywheel REAPI proof, so this PR keeps the new browser proof target scoped separately.

Boundary

This is a browser-runtime smoke target for target-class-scoped GloriousFlywheel RBE evidence. It does not prove default repo-wide RBE, the full hosted Playwright suite, Puppeteer browser execution, the full SvelteKit build, or deployment.