fix: filter scanner BT MACs in database recording

- Skip recording BT observations for addresses matching peer bt_mac
- Prevents scanners from being stored as regular devices
- Filters at database level, not just frontend display

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

src/rf_mapper/database.py

@@ -340,6 +340,11 @@ class DeviceDatabase:
         cursor = conn.cursor()
         timestamp = datetime.now().isoformat()
 
+        # Skip if this is a known scanner's BT MAC (don't record scanners as devices)
+        cursor.execute("SELECT 1 FROM peers WHERE UPPER(bt_mac) = UPPER(?)", (address,))
+        if cursor.fetchone():
+            return  # Skip scanner device
+
         # Get previous observation for movement detection
         cursor.execute("""
             SELECT rssi, distance_m, timestamp FROM rssi_history