feat: Task 5 - Add NFO Management API Endpoints (85% complete)

- Create NFO API models (11 Pydantic models)
- Implement 8 REST API endpoints for NFO management
- Register NFO router in FastAPI app
- Create 18 comprehensive API tests
- Add detailed status documentation

Endpoints:
- GET /api/nfo/{id}/check - Check NFO/media status
- POST /api/nfo/{id}/create - Create NFO & media
- PUT /api/nfo/{id}/update - Update NFO
- GET /api/nfo/{id}/content - Get NFO content
- GET /api/nfo/{id}/media/status - Media status
- POST /api/nfo/{id}/media/download - Download media
- POST /api/nfo/batch/create - Batch operations
- GET /api/nfo/missing - List missing NFOs

Remaining: Refactor to use series_app dependency pattern

src/server/fastapi_app.py

@@ -23,6 +23,7 @@ from src.server.api.auth import router as auth_router
 from src.server.api.config import router as config_router
 from src.server.api.download import router as download_router
 from src.server.api.health import router as health_router
+from src.server.api.nfo import router as nfo_router
 from src.server.api.scheduler import router as scheduler_router
 from src.server.api.websocket import router as websocket_router
 from src.server.controllers.error_controller import (
@@ -282,6 +283,7 @@ app.include_router(config_router)
 app.include_router(scheduler_router)
 app.include_router(anime_router)
 app.include_router(download_router)
+app.include_router(nfo_router)
 app.include_router(websocket_router)
 
 # Register exception handlers