Overhaul Bluetooth scanning with DBus-based BlueZ integration

Major changes:
- Add utils/bluetooth/ package with DBus scanner, fallback scanners
  (bleak, hcitool, bluetoothctl), device aggregation, and heuristics
- New unified API at /api/bluetooth/ with REST endpoints and SSE streaming
- Device observation aggregation with RSSI statistics and range bands
- Behavioral heuristics: new, persistent, beacon-like, strong+stable
- Frontend components: DeviceCard, MessageCard, RSSISparkline
- TSCM integration via get_tscm_bluetooth_snapshot() helper
- Unit tests for aggregator, heuristics, and API endpoints

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

utils/bluetooth/__init__.py

@@ -0,0 +1,70 @@
+"""
+Bluetooth scanning package for INTERCEPT.
+
+Provides unified Bluetooth scanning with DBus/BlueZ and fallback backends,
+device aggregation, RSSI statistics, and observable heuristics.
+"""
+
+from .aggregator import DeviceAggregator
+from .capability_check import check_capabilities, quick_adapter_check
+from .constants import (
+    # Range bands
+    RANGE_VERY_CLOSE,
+    RANGE_CLOSE,
+    RANGE_NEARBY,
+    RANGE_FAR,
+    RANGE_UNKNOWN,
+    # Protocols
+    PROTOCOL_BLE,
+    PROTOCOL_CLASSIC,
+    PROTOCOL_AUTO,
+    # Address types
+    ADDRESS_TYPE_PUBLIC,
+    ADDRESS_TYPE_RANDOM,
+    ADDRESS_TYPE_RANDOM_STATIC,
+    ADDRESS_TYPE_RPA,
+    ADDRESS_TYPE_NRPA,
+)
+from .heuristics import HeuristicsEngine, evaluate_device_heuristics, evaluate_all_devices
+from .models import BTDeviceAggregate, BTObservation, ScanStatus, SystemCapabilities
+from .scanner import BluetoothScanner, get_bluetooth_scanner, reset_bluetooth_scanner
+
+__all__ = [
+    # Main scanner
+    'BluetoothScanner',
+    'get_bluetooth_scanner',
+    'reset_bluetooth_scanner',
+
+    # Models
+    'BTObservation',
+    'BTDeviceAggregate',
+    'ScanStatus',
+    'SystemCapabilities',
+
+    # Aggregator
+    'DeviceAggregator',
+
+    # Heuristics
+    'HeuristicsEngine',
+    'evaluate_device_heuristics',
+    'evaluate_all_devices',
+
+    # Capability checks
+    'check_capabilities',
+    'quick_adapter_check',
+
+    # Constants
+    'RANGE_VERY_CLOSE',
+    'RANGE_CLOSE',
+    'RANGE_NEARBY',
+    'RANGE_FAR',
+    'RANGE_UNKNOWN',
+    'PROTOCOL_BLE',
+    'PROTOCOL_CLASSIC',
+    'PROTOCOL_AUTO',
+    'ADDRESS_TYPE_PUBLIC',
+    'ADDRESS_TYPE_RANDOM',
+    'ADDRESS_TYPE_RANDOM_STATIC',
+    'ADDRESS_TYPE_RPA',
+    'ADDRESS_TYPE_NRPA',
+]