fix: sync select mode widget selection

[drown0315]

Summary

Fixes Select Widget mode so tapping the live device surface synchronizes the selected widget back into the web workbench. The Widget Tree now follows the Flutter Inspector selection and the right-side selected widget panel updates from the same event.

What Changed

• Added bridge-side monitoring for Flutter Inspector selection changes via VM Service Debug Inspect events.
• Forwarded widget selection changes through the existing bridge SSE session event stream.
• Added web session event parsing and state handling for widget selection changes.
• Expanded and scrolled the Widget Tree to externally selected widgets.
• Added regression coverage for bridge event forwarding, Inspector selection publishing, web event parsing, and ancestor expansion.

Why

Select Widget mode highlighted widgets in the Flutter app, but the web app never received the selected widget id. This left the Widget Tree and selected widget panel stale after device-surface taps.

Verification

• apps/bridge: dart test
• apps/web: npm test
• apps/web: npm run build