Install browser verification runbook

[itsablabla]

Summary

• Add a Niteshift browser verification runbook for /browser, /screenshots, /demo, and /browser-profiler tasks.
• Document the verified agent-browser install, screenshot, demo, profile, and PR media workflow.

Verification

• agent-browser install
• node --check services/garza-dashboard/server.js
• agent-browser open http://localhost:3000 && agent-browser wait --text "GARZA OS" && agent-browser snapshot -i
• agent-browser screenshot /tmp/garza-dashboard-browser-verification.png --full
• agent-browser record start/stop /tmp/garza-dashboard-demo.webm
• agent-browser profiler start; agent-browser profiler stop /tmp/garza-dashboard-profile.json

Demo

Screenshots

🌒 Run on Niteshift: View Task

[charliecreates]

Non-blocking feedback (1)

1. Add an explicit fallback when /tmp/browser-preview.json is absent — docs/runbooks/niteshift-browser-verification.md#L32-L35
   The prerequisites say a known local app URL is also valid, but the current snippet always requires /tmp/browser-preview.json and will fail when that file is missing. Add a small fallback so local-only tasks can still run the flow (for example, check for the file first and otherwise set APP_URL to a documented local URL).

If you want, I can apply this update directly; reply with please fix 1.