feat: Add Meshtastic, Ubertooth, and Offline Mode support

New Features:
- Meshtastic LoRa mesh network integration
  - Real-time message streaming via SSE
  - Channel configuration with encryption
  - Node information with RSSI/SNR metrics
- Ubertooth One BLE scanner backend
  - Passive capture across all 40 BLE channels
  - Raw advertising payload access
- Offline mode with bundled assets
  - Local Leaflet, Chart.js, and fonts
  - Multiple map tile providers
  - Settings modal for configuration

Technical Changes:
- New routes: meshtastic.py, offline.py
- New utils: ubertooth_scanner.py, meshtastic.py
- New CSS/JS for meshtastic and settings
- Updated dashboard templates with conditional asset loading
- Added context processor for offline settings

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

README.md

@@ -35,9 +35,11 @@ Support the developer of this open-source project
 - **Satellite Tracking** - Pass prediction using TLE data
 - **ADS-B History** - Persistent aircraft history with reporting dashboard (Postgres optional)
 - **WiFi Scanning** - Monitor mode reconnaissance via aircrack-ng
-- **Bluetooth Scanning** - Device discovery and tracker detection
+- **Bluetooth Scanning** - Device discovery and tracker detection (with Ubertooth support)
+- **Meshtastic** - LoRa mesh network integration
 - **Spy Stations** - Number stations and diplomatic HF network database
 - **Remote Agents** - Distributed SIGINT with remote sensor nodes
+- **Offline Mode** - Bundled assets for air-gapped/field deployments
 
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