Add German FSK rating support for NFO files

- Add optional fsk field to TVShowNFO model
- Implement TMDB content ratings API integration
- Add FSK extraction and mapping (FSK 0/6/12/16/18)
- Update XML generation to prefer FSK over MPAA
- Add nfo_prefer_fsk_rating config setting
- Add 31 comprehensive tests for FSK functionality
- All 112 NFO tests passing

src/core/services/nfo_service.py

@@ -22,7 +22,7 @@ from src.core.entities.nfo_models import (
     UniqueID,
 )
 from src.core.services.tmdb_client import TMDBAPIError, TMDBClient
-from src.core.utils.image_downloader import ImageDownloader, ImageDownloadError
+from src.core.utils.image_downloader import ImageDownloader
 from src.core.utils.nfo_generator import generate_tvshow_nfo
 
 logger = logging.getLogger(__name__)
@@ -122,8 +122,11 @@ class NFOService:
                 append_to_response="credits,external_ids,images"
             )
             
+            # Get content ratings for FSK
+            content_ratings = await self.tmdb_client.get_tv_show_content_ratings(tv_id)
+            
             # Convert TMDB data to TVShowNFO model
-            nfo_model = self._tmdb_to_nfo_model(details)
+            nfo_model = self._tmdb_to_nfo_model(details, content_ratings)
             
             # Generate XML
             nfo_xml = generate_tvshow_nfo(nfo_model)
@@ -209,8 +212,11 @@ class NFOService:
                 append_to_response="credits,external_ids,images"
             )
             
+            # Get content ratings for FSK
+            content_ratings = await self.tmdb_client.get_tv_show_content_ratings(tmdb_id)
+            
             # Convert TMDB data to TVShowNFO model
-            nfo_model = self._tmdb_to_nfo_model(details)
+            nfo_model = self._tmdb_to_nfo_model(details, content_ratings)
             
             # Generate XML
             nfo_xml = generate_tvshow_nfo(nfo_model)
@@ -261,11 +267,16 @@ class NFOService:
         # Return first result (usually best match)
         return results[0]
     
-    def _tmdb_to_nfo_model(self, tmdb_data: Dict[str, Any]) -> TVShowNFO:
+    def _tmdb_to_nfo_model(
+        self,
+        tmdb_data: Dict[str, Any],
+        content_ratings: Optional[Dict[str, Any]] = None
+    ) -> TVShowNFO:
         """Convert TMDB API data to TVShowNFO model.
         
         Args:
             tmdb_data: TMDB TV show details
+            content_ratings: TMDB content ratings data
             
         Returns:
             TVShowNFO Pydantic model
@@ -362,6 +373,9 @@ class NFOService:
                 default=True
             ))
         
+        # Extract FSK rating from content ratings
+        fsk_rating = self._extract_fsk_rating(content_ratings) if content_ratings else None
+        
         # Create NFO model
         return TVShowNFO(
             title=title,
@@ -375,6 +389,7 @@ class NFOService:
             studio=[n["name"] for n in tmdb_data.get("networks", [])],
             country=[c["name"] for c in tmdb_data.get("production_countries", [])],
             ratings=ratings,
+            fsk=fsk_rating,
             tmdbid=tmdb_data.get("id"),
             imdbid=imdb_id,
             tvdbid=tvdb_id,
@@ -444,6 +459,50 @@ class NFOService:
         logger.info(f"Media download results: {results}")
         return results
     
+    def _extract_fsk_rating(self, content_ratings: Dict[str, Any]) -> Optional[str]:
+        """Extract German FSK rating from TMDB content ratings.
+        
+        Args:
+            content_ratings: TMDB content ratings response
+            
+        Returns:
+            FSK rating string (e.g., 'FSK 12') or None
+        """
+        if not content_ratings or "results" not in content_ratings:
+            return None
+        
+        # Find German rating (iso_3166_1: "DE")
+        for rating in content_ratings["results"]:
+            if rating.get("iso_3166_1") == "DE":
+                rating_value = rating.get("rating", "")
+                
+                # Map TMDB German ratings to FSK format
+                fsk_mapping = {
+                    "0": "FSK 0",
+                    "6": "FSK 6",
+                    "12": "FSK 12",
+                    "16": "FSK 16",
+                    "18": "FSK 18",
+                }
+                
+                # Try direct mapping
+                if rating_value in fsk_mapping:
+                    return fsk_mapping[rating_value]
+                
+                # Try to extract number from rating string (ordered from highest to lowest to avoid partial matches)
+                for key in ["18", "16", "12", "6", "0"]:
+                    if key in rating_value:
+                        return fsk_mapping[key]
+                
+                # Return as-is if it already starts with FSK
+                if rating_value.startswith("FSK"):
+                    return rating_value
+                
+                logger.debug(f"Unmapped German rating: {rating_value}")
+                return None
+        
+        return None
+    
     async def close(self):
         """Clean up resources."""
         await self.tmdb_client.close()

src/core/services/tmdb_client.py

@@ -191,6 +191,17 @@ class TMDBClient:
         
         return await self._request(f"tv/{tv_id}", params)
     
+    async def get_tv_show_content_ratings(self, tv_id: int) -> Dict[str, Any]:
+        """Get content ratings for a TV show.
+        
+        Args:
+            tv_id: TMDB TV show ID
+            
+        Returns:
+            Content ratings by country
+        """
+        return await self._request(f"tv/{tv_id}/content_ratings")
+    
     async def get_tv_show_external_ids(self, tv_id: int) -> Dict[str, Any]:
         """Get external IDs (IMDB, TVDB) for a TV show.