debug: Add logging to diagnose Flow movie processing issue

Added debug logs to understand why Flow (2019) isn't calling external APIs
while Ambush (2023) works correctly. This will show:

- should_query calculation and reasoning
- _decide_movie_dates entry point and logic path
- Whether existing database data is being used incorrectly

This should help identify why digital release date lookup works for some
movies but not others with identical database states.

nfoguard.py

@@ -1005,6 +1005,8 @@ class MovieProcessor:
                 (config.movie_poll_mode == "if_missing" and existing and not existing.get("dateadded"))
             )
             
+            _log("DEBUG", f"Movie {imdb_id}: should_query={should_query}, poll_mode={config.movie_poll_mode}, existing={bool(existing)}, has_dateadded={bool(existing and existing.get('dateadded')) if existing else False}")
+            
             # Use existing movie date decision logic
             dateadded, source, released = self._decide_movie_dates(imdb_id, movie_path, should_query, existing)
         
@@ -1055,7 +1057,10 @@ class MovieProcessor:
     
     def _decide_movie_dates(self, imdb_id: str, movie_path: Path, should_query: bool, existing: Optional[Dict]) -> Tuple[str, str, Optional[str]]:
         """Decide movie dates based on configuration and available data"""
+        _log("DEBUG", f"_decide_movie_dates for {imdb_id}: should_query={should_query}, existing={existing}")
+        
         if not should_query and existing:
+            _log("DEBUG", f"Using existing data without querying: dateadded={existing.get('dateadded')}, source={existing.get('source')}")
             return existing["dateadded"], existing["source"], existing.get("released")
         
         # Query Radarr for movie info