chore: Bump version to v2.18.0

Bluetooth enhancements (service data inspector, appearance codes, MAC
cluster tracking, behavioral flags, IRK badges, distance estimation),
ACARS SoapySDR multi-backend support, dump1090 stale process cleanup,
GPS error state, and proximity radar/signal card UI improvements.

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

utils/gps.py

@@ -483,3 +483,181 @@ def get_current_position() -> GPSPosition | None:
     if client:
         return client.position
     return None
+
+
+# ============================================
+# GPS device detection and gpsd auto-start
+# ============================================
+
+_gpsd_process: 'subprocess.Popen | None' = None
+_gpsd_process_lock = threading.Lock()
+
+
+def detect_gps_devices() -> list[dict]:
+    """
+    Detect connected GPS serial devices.
+
+    Returns list of dicts with 'path' and 'description' keys.
+    """
+    import glob
+    import os
+    import platform
+
+    devices: list[dict] = []
+    system = platform.system()
+
+    if system == 'Linux':
+        # Common USB GPS device paths
+        patterns = ['/dev/ttyUSB*', '/dev/ttyACM*']
+        for pattern in patterns:
+            for path in sorted(glob.glob(pattern)):
+                desc = _describe_device_linux(path)
+                devices.append({'path': path, 'description': desc})
+
+        # Also check /dev/serial/by-id for descriptive names
+        serial_dir = '/dev/serial/by-id'
+        if os.path.isdir(serial_dir):
+            for name in sorted(os.listdir(serial_dir)):
+                full = os.path.join(serial_dir, name)
+                real = os.path.realpath(full)
+                # Skip if we already found this device
+                if any(d['path'] == real for d in devices):
+                    # Update description with the more descriptive name
+                    for d in devices:
+                        if d['path'] == real:
+                            d['description'] = name
+                    continue
+                devices.append({'path': real, 'description': name})
+
+    elif system == 'Darwin':
+        # macOS: USB serial devices (prefer cu. over tty. for outgoing)
+        patterns = ['/dev/cu.usbmodem*', '/dev/cu.usbserial*']
+        for pattern in patterns:
+            for path in sorted(glob.glob(pattern)):
+                desc = _describe_device_macos(path)
+                devices.append({'path': path, 'description': desc})
+
+    # Sort: devices with GPS-related descriptions first
+    gps_keywords = ('gps', 'gnss', 'u-blox', 'ublox', 'nmea', 'sirf', 'navigation')
+    devices.sort(key=lambda d: (
+        0 if any(k in d['description'].lower() for k in gps_keywords) else 1
+    ))
+
+    return devices
+
+
+def _describe_device_linux(path: str) -> str:
+    """Get a human-readable description of a Linux serial device."""
+    import os
+    basename = os.path.basename(path)
+    # Try to read from sysfs
+    try:
+        # /sys/class/tty/ttyUSB0/device/../product
+        sysfs = f'/sys/class/tty/{basename}/device/../product'
+        if os.path.exists(sysfs):
+            with open(sysfs) as f:
+                return f.read().strip()
+    except Exception:
+        pass
+    return basename
+
+
+def _describe_device_macos(path: str) -> str:
+    """Get a description of a macOS serial device."""
+    import os
+    return os.path.basename(path)
+
+
+def is_gpsd_running(host: str = 'localhost', port: int = 2947) -> bool:
+    """Check if gpsd is reachable."""
+    import socket
+    try:
+        sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        sock.settimeout(1.0)
+        sock.connect((host, port))
+        sock.close()
+        return True
+    except Exception:
+        return False
+
+
+def start_gpsd_daemon(device_path: str, host: str = 'localhost',
+                      port: int = 2947) -> tuple[bool, str]:
+    """
+    Start gpsd daemon pointing at the given device.
+
+    Returns (success, message) tuple.
+    """
+    import shutil
+    import subprocess
+
+    global _gpsd_process
+
+    with _gpsd_process_lock:
+        # Already running?
+        if is_gpsd_running(host, port):
+            return True, 'gpsd already running'
+
+        gpsd_bin = shutil.which('gpsd')
+        if not gpsd_bin:
+            return False, 'gpsd not installed'
+
+        # Stop any existing managed process
+        stop_gpsd_daemon()
+
+        try:
+            import os
+            if not os.path.exists(device_path):
+                return False, f'Device {device_path} not found'
+
+            cmd = [gpsd_bin, '-N', '-n', '-S', str(port), device_path]
+            logger.info(f"Starting gpsd: {' '.join(cmd)}")
+            print(f"[GPS] Starting gpsd: {' '.join(cmd)}", flush=True)
+
+            _gpsd_process = subprocess.Popen(
+                cmd,
+                stdout=subprocess.DEVNULL,
+                stderr=subprocess.PIPE,
+            )
+
+            # Give gpsd a moment to start
+            import time
+            time.sleep(1.5)
+
+            if _gpsd_process.poll() is not None:
+                stderr = ''
+                if _gpsd_process.stderr:
+                    stderr = _gpsd_process.stderr.read().decode('utf-8', errors='ignore').strip()
+                msg = f'gpsd exited with code {_gpsd_process.returncode}'
+                if stderr:
+                    msg += f': {stderr}'
+                return False, msg
+
+            # Verify it's listening
+            if is_gpsd_running(host, port):
+                return True, f'gpsd started on {device_path}'
+            else:
+                return False, 'gpsd started but not accepting connections'
+
+        except Exception as e:
+            logger.error(f"Failed to start gpsd: {e}")
+            return False, str(e)
+
+
+def stop_gpsd_daemon() -> None:
+    """Stop the managed gpsd daemon process."""
+    global _gpsd_process
+
+    with _gpsd_process_lock:
+        if _gpsd_process and _gpsd_process.poll() is None:
+            try:
+                _gpsd_process.terminate()
+                _gpsd_process.wait(timeout=3.0)
+            except Exception:
+                try:
+                    _gpsd_process.kill()
+                except Exception:
+                    pass
+            logger.info("Stopped gpsd daemon")
+            print("[GPS] Stopped gpsd daemon", flush=True)
+        _gpsd_process = None