fix: Add fallback to GUIDED mode if GUIDED_NOGPS is unavailable when GPS is denied.

src/drone_controller.py

@@ -278,7 +278,10 @@ def main():
         # Configure for GPS-denied if needed
         if not args.gps:
             drone.setup_gps_denied()
-            drone.set_mode("GUIDED_NOGPS")
+            # Try GUIDED_NOGPS first (ArduCopter), fallback to GUIDED
+            if not drone.set_mode("GUIDED_NOGPS"):
+                print("[INFO] GUIDED_NOGPS not available, using GUIDED")
+                drone.set_mode("GUIDED")
         else:
             drone.set_mode("GUIDED")