Task 2: guard SeriesApp NFOService init on NFOServiceFactory fallback and document config-only TMDB API key support

src/core/SeriesApp.py

@@ -171,23 +171,26 @@ class SeriesApp:
         # Initialize empty list - series loaded later via load_series_from_list()
         # No need to call _init_list_sync() anymore
         
-        # Initialize NFO service if TMDB API key is configured
+        # Initialize NFO service if a TMDB API key is configured
         self.nfo_service: Optional[NFOService] = None
-        if settings.tmdb_api_key:
-            try:
-                from src.core.services.nfo_factory import get_nfo_factory
-                factory = get_nfo_factory()
-                self.nfo_service = factory.create()
-                logger.info("NFO service initialized successfully")
-            except (ValueError, Exception) as e:  # pylint: disable=broad-except
-                logger.warning(
-                    "Failed to initialize NFO service: %s", str(e)
-                )
-                self.nfo_service = None
+        try:
+            from src.core.services.nfo_factory import get_nfo_factory
+
+            factory = get_nfo_factory()
+            self.nfo_service = factory.create()
+            logger.info("NFO service initialized successfully")
+        except ValueError:
+            logger.info(
+                "NFO service not available — TMDB API key not configured"
+            )
+            self.nfo_service = None
+        except Exception as e:  # pylint: disable=broad-except
+            logger.warning("Failed to initialize NFO service: %s", str(e))
+            self.nfo_service = None
 
         logger.info(
             "SeriesApp initialized for directory: %s",
-            directory_to_search
+            directory_to_search,
         )
 
     @property