fix: radiosonde config path and dependency detection

- Pass config file path (not directory) to auto_rx -c flag
- Use absolute paths in generated station.cfg since auto_rx runs
  with cwd set to its install directory
- Teach dependency checker about auto_rx.py at /opt install path
  so the "missing dependency" banner no longer appears

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

routes/radiosonde.py

@@ -85,11 +85,13 @@ def generate_station_cfg(
     udp_port: int = RADIOSONDE_UDP_PORT,
 ) -> str:
     """Generate a station.cfg for radiosonde_auto_rx and return the file path."""
-    cfg_dir = os.path.join('data', 'radiosonde')
-    os.makedirs(cfg_dir, exist_ok=True)
+    cfg_dir = os.path.abspath(os.path.join('data', 'radiosonde'))
+    log_dir = os.path.join(cfg_dir, 'logs')
+    os.makedirs(log_dir, exist_ok=True)
     cfg_path = os.path.join(cfg_dir, 'station.cfg')
 
     # Minimal station.cfg that auto_rx needs
+    # Use absolute paths since auto_rx runs with cwd set to its install dir
     cfg = f"""# Auto-generated by INTERCEPT for radiosonde_auto_rx
 [search_params]
 min_freq = {freq_min}
@@ -122,7 +124,7 @@ station_alt = 0.0
 
 [logging]
 per_sonde_log = True
-log_directory = ./data/radiosonde/logs
+log_directory = {log_dir}
 
 [advanced]
 web_host = 127.0.0.1
@@ -414,12 +416,12 @@ def start_radiosonde():
         bias_t=bias_t,
     )
 
-    # Build command
-    cfg_dir = os.path.dirname(os.path.abspath(cfg_path))
+    # Build command - auto_rx -c expects a file path, not a directory
+    cfg_abs = os.path.abspath(cfg_path)
     if auto_rx_path.endswith('.py'):
-        cmd = [sys.executable, auto_rx_path, '-c', cfg_dir]
+        cmd = [sys.executable, auto_rx_path, '-c', cfg_abs]
     else:
-        cmd = [auto_rx_path, '-c', cfg_dir]
+        cmd = [auto_rx_path, '-c', cfg_abs]
 
     # Set cwd to the auto_rx directory so 'from autorx.scan import ...' works
     auto_rx_dir = os.path.dirname(os.path.abspath(auto_rx_path))