Check common paths for dump1090 when not in PATH

Flask apps may run with a restricted PATH that doesn't include
/usr/local/bin. Now explicitly checks common installation locations.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

routes/adsb.py

@@ -3,6 +3,7 @@
 from __future__ import annotations
 
 import json
+import os
 import queue
 import shutil
 import socket
@@ -21,6 +22,30 @@ adsb_bp = Blueprint('adsb', __name__, url_prefix='/adsb')
 # Track if using service
 adsb_using_service = False
 
+# Common installation paths for dump1090 (when not in PATH)
+DUMP1090_PATHS = [
+    '/usr/local/bin/dump1090',
+    '/usr/local/bin/dump1090-fa',
+    '/usr/local/bin/dump1090-mutability',
+    '/usr/bin/dump1090',
+    '/usr/bin/dump1090-fa',
+    '/usr/bin/dump1090-mutability',
+]
+
+
+def find_dump1090():
+    """Find dump1090 binary, checking PATH and common locations."""
+    # First try PATH
+    for name in ['dump1090', 'dump1090-mutability', 'dump1090-fa']:
+        path = shutil.which(name)
+        if path:
+            return path
+    # Check common installation paths directly
+    for path in DUMP1090_PATHS:
+        if os.path.isfile(path) and os.access(path, os.X_OK):
+            return path
+    return None
+
 
 def check_dump1090_service():
     """Check if dump1090 SBS port (30003) is available."""
@@ -154,7 +179,7 @@ def parse_sbs_stream(service_addr):
 def check_adsb_tools():
     """Check for ADS-B decoding tools."""
     return jsonify({
-        'dump1090': shutil.which('dump1090') is not None or shutil.which('dump1090-mutability') is not None or shutil.which('dump1090-fa') is not None,
+        'dump1090': find_dump1090() is not None,
         'rtl_adsb': shutil.which('rtl_adsb') is not None
     })
 
@@ -174,10 +199,10 @@ def start_adsb():
     gain = data.get('gain', '40')
     device = data.get('device', '0')
 
-    dump1090_path = shutil.which('dump1090') or shutil.which('dump1090-mutability') or shutil.which('dump1090-fa')
+    dump1090_path = find_dump1090()
 
     if not dump1090_path:
-        return jsonify({'status': 'error', 'message': 'dump1090 not found.'})
+        return jsonify({'status': 'error', 'message': 'dump1090 not found. Install dump1090/dump1090-fa or ensure it is in /usr/local/bin/'})
 
     cmd = [dump1090_path, '--net', '--gain', gain, '--device-index', str(device), '--quiet']