ci: harden website e2e and examples deploy gating

[blove]

Summary

Harden the website e2e and examples deploy gates without changing the overall CI topology.

• Move website Playwright's local server default from shared localhost:3000 to an isolated 127.0.0.1:4308.
• Disable implicit local server reuse unless PLAYWRIGHT_REUSE_EXISTING_SERVER=true is set explicitly.
• Fix the examples production deploy change detector to watch real example-impacting libraries instead of stale libs/angular, including langgraph, ag-ui, a2ui, partial-json, and example-layouts.

Root Cause

The website e2e config could attach to whatever happened to be running on local port 3000, which can make local verification test the wrong app. The examples deploy gate also still referenced a removed libs/angular path and missed libraries that are now part of the example apps' runtime surface.

Verification

• npx nx e2e website --skip-nx-cache — 11 passed
• npx nx lint website --skip-nx-cache — passed with existing apps/website/instrumentation-client.ts non-null assertion warning
• npx nx build website --skip-nx-cache
• python3 parsed .github/workflows/ci.yml with PyYAML
• shell predicate check for examples deploy paths
• git diff --check

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Project	Deployment	Actions	Updated (UTC)
cacheplane	Ready	Preview, Comment	May 7, 2026 5:30pm