ci: cache e2e setup and reuse dist

[PBandDev]

Summary

• cache the built extension artifact in CI and restore it for the E2E job instead of rebuilding
• cache Playwright browsers and the pinned .test-comfy environment for CI and publish runs
• align local docs and scripts so pnpm ci:local runs the full CI workflow with act

Testing

• pnpm build
• pnpm typecheck
• pnpm test
• pnpm ci:local