Add Puppeteer Chromium RBE smoke target

[Jesssullivan]

Summary

• add //:puppeteer_chromium_smoke as a narrow Bazel js_test
• launch Puppeteer against an explicit Chromium executable path instead of lifecycle browser downloads
• update the GloriousFlywheel pilot docs to include the Puppeteer target-class boundary

Validation

• git diff --check
• npx prettier --check scripts/run-puppeteer-chromium-bazel.mjs README.md
• PUPPETEER_EXECUTABLE_PATH='/Applications/Google Chrome.app/Contents/MacOS/Google Chrome' npx --yes @bazel/bazelisk test --config=ci --config=no-remote-cache //:puppeteer_chromium_smoke
• GF REAPI Cell Proof: https://github.com/tinyland-inc/GloriousFlywheel/actions/runs/25777472760
  • target: //:puppeteer_chromium_smoke
  • command: bazel test --config=ci-cached
  • force execution: true
  • executor/cache: grpc://gf-reapi-cell.gf-rbe.svc.cluster.local:8980
  • image digest: sha256:a567696e341f6eb0589ece9efd6014a2133a4f10831bdad31e8dd84055eff8a0
  • platform: gloriousflywheel-rbe-linux-x86_64
  • worker: gf-reapi-cell-ff5f7699f-2td2v
  • Bazel result: 2331 processes: 1477 internal, 855 remote; //:puppeteer_chromium_smoke PASSED in 1.1s

Boundary

This proves a minimal public Puppeteer/Chromium target candidate for GloriousFlywheel REAPI evidence. It does not prove full Puppeteer suites, the hosted Playwright regression suite, full SvelteKit build RBE, broad/default repo RBE, or RustFS-backed CAS/action-cache authority.

Linear: TIN-1132