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>

CHANGELOG.md

@@ -0,0 +1,78 @@
+# Changelog
+
+All notable changes to RF Mapper are documented here.
+
+Format based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
+
+---
+
+## [0.3.0] - 2026-02-01
+
+### Added
+
+- **3D Map Visualization** - MapLibre GL JS integration with building extrusion
+- **Floor-based positioning** - Assign devices to floors, filter by floor
+- **SQLite database** - Historical device tracking with 7 tables
+- **Historical data API** - 15+ new endpoints for device history, stats, alerts
+- **Live BT tracking mode** - 4-second scan interval with auto-start
+- **Movement detection** - Statistical analysis (5-sample avg + 2σ threshold)
+- **bleak BLE scanning** - Reliable RSSI via D-Bus/BlueZ (replaced hcitool)
+- **Floor persistence** - Floor assignments saved in database
+- **Popup persistence** - Device popups stay open during live updates
+- **Custom distance override** - Manual distance setting via popup
+- **Position smoothing** - Statistical averaging for stable positions
+- **Filter-aware scanning** - Skip WiFi/BT based on toggle state
+- **Auto-scan feature** - Background scanning with configurable interval
+- **Device labeling** - Custom names via API
+- **Favorite devices** - Mark important devices
+- **Alert system** - New device detection, activity alerts
+- **Activity patterns** - Hourly/daily usage analysis
+- **Database cleanup** - Automatic and manual data retention
+
+### Changed
+
+- Switched from `hcitool` to `bleak` Python library for BLE scanning
+- Improved distance estimation algorithm
+- Enhanced web UI with real-time updates
+
+### Fixed
+
+- BT RSSI acquisition now reliable (bleak library)
+- Floor assignments persist across page reloads
+- Popups no longer close during live tracking
+
+---
+
+## [0.2.0] - 2026-01-25
+
+### Added
+
+- **World Map view** - Leaflet.js integration with device markers
+- **2.5D visualization** - Height-based display
+- **Auto-identify Bluetooth** - Device type inference from name/manufacturer
+- **OUI lookup** - Manufacturer identification from MAC address
+- **Signal quality indicators** - Visual strength representation
+- **Request profiling** - Optional per-request performance analysis
+- **Request logging** - Optional request logging to file
+
+### Changed
+
+- Improved CLI output formatting
+- Better error handling for scan failures
+
+---
+
+## [0.1.0] - 2026-01-15
+
+### Added
+
+- Initial release
+- **WiFi scanning** - Uses `iw` command
+- **Bluetooth scanning** - Uses `hcitool` and `bluetoothctl`
+- **CLI interface** - scan, visualize, analyze, list, config commands
+- **Web interface** - Flask-based dashboard
+- **Radar visualization** - ASCII and web-based radar view
+- **Distance estimation** - RSSI-based path loss model
+- **Configuration system** - YAML config with environment variable overrides
+- **JSON data storage** - Scan results saved as JSON files
+- **GPS support** - Reference position for mapping