* fix: preserve lastEventId in SSE path and add proxy heartbeat
- Extract event.id from SSE stream events in event-pipeline.ts so that
reconnects carry the correct Last-Event-ID header for gapless replay.
- Emit :heartbeat comment every 20s in the direct SSE proxy to keep
the UI heartbeat watchdog from aborting idle connections.
* fix: handle SSE metadata through SDK callback
* Guard SSE proxy heartbeats
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Co-authored-by: Bohdan Triapitsyn <artmore@protonmail.com>
Introduce a dedicated Quick Open dialog, wire it to Cmd+P and the macOS app menu, and show file-type icons in quick-open results so file navigation matches the rest of the app.
