fix(antigravity): add debug logging for non-data URL images

Logs a debug message when skipping non-data URL images, helping
developers troubleshoot why images may not appear in requests.

Author: FammasMaz

src/rotator_library/providers/antigravity_provider.py

@@ -2424,6 +2424,7 @@ def _parse_image_url(self, image_url: Dict[str, Any]) -> Optional[Dict[str, Any]
         """Parse image URL into Gemini inlineData format."""
         url = image_url.get("url", "")
         if not url.startswith("data:"):
+            lib_logger.debug(f"Skipping non-data URL image: {url[:100]}...")
             return None
 
         try: