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>

docs/index.html

@@ -130,6 +130,18 @@
                     <h3>Remote Agents</h3>
                     <p>Distributed signal intelligence with remote sensor nodes. Deploy agents across multiple locations and aggregate data to a central controller.</p>
                 </div>
+
+                <div class="feature-card">
+                    <div class="feature-icon">📴</div>
+                    <h3>Offline Mode</h3>
+                    <p>Run without internet using bundled assets. Choose from multiple map tile providers or use your own local tile server.</p>
+                </div>
+
+                <div class="feature-card">
+                    <div class="feature-icon">📡</div>
+                    <h3>Meshtastic</h3>
+                    <p>LoRa mesh network integration. Connect to Meshtastic devices for decentralized, long-range communication monitoring.</p>
+                </div>
             </div>
         </div>
     </section>