v2.2.0

v2.2.0 — stability, performance & UX overhaul

Connection reliability:
- WebSocket heartbeat (30s ping/pong) detects dead connections
- Exponential reconnect backoff (2s → 30s max), never gives up permanently
- Removed duplicate retry mechanism (startInitRetryWatchdog)
- connect() now closes stale WebSocket before creating new one

Memory & listener management:
- Fixed uncancellable setTimeout after meeting ends (cleared in before-quit)
- Removed duplicate autoUpdater listeners (fixes duplicate events to renderer)
- Blocked page polling interval stops when zone ends
- Added .astro/ to .gitignore

Tray experience:
- Wired minimizeToTray setting (previously dead setting)

Extension UI:
- Removed broken settings button (was triggering reconnect)
- Synced all changes across chrome-release and firefox-release copies

Branding:
- Updated docs/index.html from purple (#6366f1/#a855f7) to green (#1D9E75/#059669)

Version: 2.2.0
Reports: PROJECT_HEALTH_REPORT.md, PERFORMANCE_REPORT.md,
         SECURITY_AUDIT.md, MEMORY_AUDIT.md,
         VERSION_AUDIT_REPORT.md, UX_REVIEW.md