Add `connectCDP()` to BrowserManager: connects to a running browser via
Chrome DevTools Protocol. All existing browse commands work unchanged
through Playwright's abstraction layer.
- chrome-launcher.ts: browser discovery, CDP probe, auto-relaunch with rollback
- browser-manager.ts: connectCDP(), mode guards (close/closeTab/recreateContext/handoff),
auto-reconnect on browser restart, getRefMap() for extension API
- server.ts: CDP branch in start(), /health gains mode field, /refs endpoint,
idle timer only resets on /command (not passive endpoints)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
