Fix Issue 5: Create NFOServiceFactory for centralized initialization

- Created NFOServiceFactory in src/core/services/nfo_factory.py
- Enforces configuration precedence: explicit params > ENV > config.json
- Provides create() and create_optional() methods
- Singleton factory instance via get_nfo_factory()
- Updated 4 files to use factory (nfo.py, SeriesApp.py, series_manager_service.py, nfo_cli.py)
- Fixed test mocks: added ensure_folder_with_year(), corrected dependency test
- Tests: 17/18 NFO passing, 15/16 anime passing
- Resolves Code Duplication 2 (NFO initialization)

src/server/api/nfo.py

@@ -14,6 +14,7 @@ from fastapi import APIRouter, Depends, HTTPException, status
 from src.config.settings import settings
 from src.core.entities.series import Serie
 from src.core.SeriesApp import SeriesApp
+from src.core.services.nfo_factory import get_nfo_factory
 from src.core.services.nfo_service import NFOService
 from src.core.services.tmdb_client import TMDBAPIError
 from src.server.models.nfo import (
@@ -46,32 +47,16 @@ async def get_nfo_service() -> NFOService:
     Raises:
         HTTPException: If NFO service not configured
     """
-    # Check if TMDB API key is in settings
-    tmdb_api_key = settings.tmdb_api_key
-    
-    # If not in settings, try to load from config.json
-    if not tmdb_api_key:
-        try:
-            from src.server.services.config_service import get_config_service
-            config_service = get_config_service()
-            config = config_service.load_config()
-            if config.nfo and config.nfo.tmdb_api_key:
-                tmdb_api_key = config.nfo.tmdb_api_key
-        except Exception:
-            pass  # Config loading failed, tmdb_api_key remains None
-    
-    if not tmdb_api_key:
+    try:
+        # Use centralized factory for consistent initialization
+        factory = get_nfo_factory()
+        return factory.create()
+    except ValueError as e:
+        # Factory raises ValueError if API key not configured
         raise HTTPException(
             status_code=status.HTTP_503_SERVICE_UNAVAILABLE,
-            detail="NFO service not configured. TMDB API key required."
-        )
-    
-    return NFOService(
-        tmdb_api_key=tmdb_api_key,
-        anime_directory=settings.anime_directory,
-        image_size=settings.nfo_image_size,
-        auto_create=settings.nfo_auto_create
-    )
+            detail=str(e)
+        ) from e
 
 
 @router.get("/{serie_id}/check", response_model=NFOCheckResponse)