feat: wire BLE handler in ingestion server for ble_scan broadcast

The BLE handler was set but never invoked when BLE messages arrived
from nodes. Replace the TODO with actual bleHandler call so BLE scan
data flows to the registry, enabling the existing 5s ble_scan
WebSocket broadcast to dashboard clients.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

mothership/internal/ingestion/server.go

@@ -533,7 +533,12 @@ func (s *Server) handleJSONMessage(nc *NodeConnection, data []byte) {
 		nc.LastHealthTime = time.Now()
 
 	case *BLEMessage:
-		// TODO: forward BLE data to identity matcher
+		s.mu.RLock()
+		handler := s.bleHandler
+		s.mu.RUnlock()
+		if handler != nil {
+			handler(nc.MAC, msg.Devices)
+		}
 
 	case *MotionHintMessage:
 		s.mu.RLock()