fix: skip Bluetooth scanning on Termux/Android

Bleak requires D-Bus which isn't available on Android. Detect Termux
environment and skip both Classic BT and BLE scanning gracefully.

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

src/rf_mapper/scanner.py

@@ -4,12 +4,19 @@ import subprocess
 import re
 import json
 import asyncio
+import os
 from datetime import datetime
 from pathlib import Path
 from dataclasses import dataclass, asdict
 
 from bleak import BleakScanner
 
+
+def is_termux() -> bool:
+    """Detect if running in Termux (Android)."""
+    return os.environ.get('TERMUX_VERSION') is not None or \
+           os.path.exists('/data/data/com.termux')
+
 from .oui import OUILookup
 from .bluetooth_class import BluetoothClassDecoder
 from .distance import estimate_distance, rssi_to_quality, rssi_bar
@@ -184,7 +191,10 @@ class RFScanner:
         """
         devices = []
 
-        # Classic Bluetooth scan
+        # Classic Bluetooth scan (not supported on Termux/Android)
+        if is_termux():
+            print("Skipping Classic BT scan (not supported on Termux)")
+        else:
             try:
                 print(f"Scanning Classic Bluetooth ({timeout} seconds)...")
                 result = subprocess.run(
@@ -217,7 +227,10 @@ class RFScanner:
             except Exception as e:
                 print(f"Classic BT scan error: {e}")
 
-        # BLE scan using bleak
+        # BLE scan using bleak (not supported on Termux/Android)
+        if is_termux():
+            print("Skipping BLE scan (not supported on Termux)")
+        else:
             try:
                 print(f"Scanning BLE devices ({timeout} seconds)...")