feat: add Home Assistant integration and improve CLI/UI

Home Assistant Integration:
- New homeassistant.py module with webhook support
- Webhooks for scan results, new devices, and device departures
- Absence detection with configurable timeout
- Documentation in docs/HOME_ASSISTANT.md

CLI Improvements:
- Replace 'web' command with start/stop/restart/status
- Background daemon mode with PID file management
- Foreground mode for debugging (--foreground)

Web UI Enhancements:
- Improved device list styling and layout
- Better floor assignment UI
- Enhanced map visualization

Documentation:
- Add CHANGELOG.md
- Add docs/API.md with full endpoint reference
- Add docs/CHEATSHEET.md for quick reference
- Update project documentation

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

ROADMAP.md

@@ -49,7 +49,7 @@
 
 ---
 
-## v0.4.0 - Multilateration & Positioning
+## v0.6.0 - Multilateration & Positioning
 
 - [ ] Multi-point scanning (move scanner, record positions)
 - [ ] Trilateration algorithm for device positioning
@@ -61,7 +61,7 @@
 
 ---
 
-## v0.5.0 - Persistence & History
+## v0.7.0 - Persistence & History
 
 - [x] SQLite database for scan history
 - [x] Device tracking over time
@@ -73,14 +73,24 @@
 
 ---
 
-## v0.6.0 - Alerts & Automation
+## v0.4.0 - Home Assistant Integration (COMPLETED)
 
-- [ ] New device alerts
+- [x] Webhook-based HA communication
+- [x] Scan results webhook (device_tracker.see)
+- [x] New device alerts webhook
+- [x] Device departure detection webhook
+- [x] Configurable timeout for departure detection
+
+---
+
+## v0.5.0 - Alerts & Automation
+
+- [x] New device alerts (via HA webhook)
 - [ ] Signal threshold alerts
-- [ ] Webhook notifications
-- [ ] Home Assistant integration (MQTT)
-- [ ] Presence detection automation
-- [ ] Device absence detection
+- [x] Webhook notifications
+- [ ] Home Assistant MQTT auto-discovery
+- [x] Presence detection automation (via HA webhook)
+- [x] Device absence detection (via HA webhook)
 - [ ] Scheduled reports
 
 ---