feat: replace hcitool BLE scanning with bleak library

Use bleak's BleakScanner for BLE device discovery instead of
hcitool lescan subprocess. Provides real RSSI values from
advertisement packets instead of hardcoded -70dB estimate.

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

src/rf_mapper/scanner.py

@@ -3,10 +3,13 @@
 import subprocess
 import re
 import json
+import asyncio
 from datetime import datetime
 from pathlib import Path
 from dataclasses import dataclass, asdict
 
+from bleak import BleakScanner
+
 from .oui import OUILookup
 from .bluetooth_class import BluetoothClassDecoder
 from .distance import estimate_distance, rssi_to_quality, rssi_bar
@@ -214,33 +217,40 @@ class RFScanner:
         except Exception as e:
             print(f"Classic BT scan error: {e}")
 
-        # BLE scan
+        # BLE scan using bleak
         try:
             print(f"Scanning BLE devices ({timeout} seconds)...")
-            result = subprocess.run(
+
-                ['sudo', 'timeout', str(timeout), 'hcitool', 'lescan', '--duplicates'],
+            async def _ble_scan():
-                capture_output=True,
+                return await BleakScanner.discover(
-                text=True,
+                    timeout=timeout,
-                timeout=timeout + 5
+                    return_adv=True
                 )
 
-            seen_addrs = {d.address for d in devices}
+            ble_results = asyncio.run(_ble_scan())
-            for line in result.stdout.split('\n'):
-                match = re.match(r'([0-9A-Fa-f:]+)\s*(.*)', line)
-                if match:
-                    addr = match.group(1)
-                    name = match.group(2).strip() or '<unknown>'
 
+            seen_addrs = {d.address for d in devices}
+            for device, adv_data in ble_results.values():
+                addr = device.address
                 if addr not in seen_addrs and addr != 'LE':
                     seen_addrs.add(addr)
+
+                    name = device.name or adv_data.local_name or '<unknown>'
+                    rssi = adv_data.rssi  # Real RSSI from advertisement
                     manufacturer = self.oui_lookup.lookup(addr)
 
-                        # Try to infer device type from name first, then manufacturer
+                    # Extract manufacturer data if available
+                    if adv_data.manufacturer_data and not manufacturer:
+                        # First 2 bytes are company ID
+                        for company_id in adv_data.manufacturer_data.keys():
+                            manufacturer = f"Company ID: {company_id}"
+                            break
+
+                    # Infer device type
                     inferred_type = infer_device_type_from_name(name)
                     if not inferred_type:
                         inferred_type = infer_device_type_from_manufacturer(manufacturer)
 
-                        # Mark randomized MAC devices if still unknown
                     if not inferred_type:
                         if is_random_mac(addr):
                             device_type = "BLE Device (Random MAC)"
@@ -252,7 +262,7 @@ class RFScanner:
                     devices.append(BluetoothDevice(
                         address=addr,
                         name=name,
-                            rssi=-70,  # Default estimate for BLE
+                        rssi=rssi,  # Real RSSI instead of -70
                         device_class="BLE",
                         device_type=device_type,
                         manufacturer=manufacturer