docs: update TODO with completed features

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

TODO.md

@@ -36,7 +36,7 @@
 - [x] Background sync thread
 - [x] WebSocket real-time sync (instead of polling)
 - [ ] Automatic peer discovery via mDNS/Bonjour
-- [ ] Sync RSSI history for trilateration
+- [x] Sync RSSI history for trilateration
 - [ ] Web UI for peer management
 - [ ] Sync conflict resolution UI
 
@@ -65,7 +65,7 @@
 - [ ] Environment presets (office, home, warehouse)
 - [ ] Wall attenuation factor
 - [ ] Multi-floor path loss adjustment
-- [ ] Trilateration from multiple scan points
+- [x] Trilateration from multiple scan points
 - [ ] Kalman filter for position smoothing
 - [ ] Dead reckoning with IMU (if available)
 - [ ] Fingerprinting-based positioning
@@ -244,6 +244,10 @@
 - [x] Bidirectional device metadata sync
 - [x] Source scanner tracking for synced devices
 - [x] Peer scanner markers on 3D map
+- [x] WebSocket real-time sync
+- [x] Termux/Android environment detection with prerequisite checks
+- [x] Multi-scanner trilateration for device positioning
+- [x] Signal coverage heat map visualization
 
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