feat: Add NFO configuration settings (Task 7)

- Added NFOConfig model with TMDB API key, auto-create, media downloads, image size settings
- Created NFO settings section in UI with form fields and validation
- Implemented nfo-config.js module for loading, saving, and testing TMDB connection
- Added TMDB API key validation endpoint (POST /api/config/tmdb/validate)
- Integrated NFO config into AppConfig and ConfigUpdate models
- Added 5 unit tests for NFO config model validation
- Added API test for TMDB validation endpoint
- All 16 config model tests passing, all 10 config API tests passing
- Documented in docs/task7_status.md (100% complete)

src/server/api/config.py

@@ -371,3 +371,59 @@ def reset_config(
             detail=f"Failed to reset config: {e}"
         ) from e
 
+
+@router.post("/tmdb/validate", response_model=Dict[str, Any])
+async def validate_tmdb_key(
+    api_key_data: Dict[str, str], auth: dict = Depends(require_auth)
+) -> Dict[str, Any]:
+    """Validate TMDB API key by making a test request.
+
+    Args:
+        api_key_data: Dictionary with 'api_key' field
+        auth: Authentication token (required)
+
+    Returns:
+        Validation result with success status and message
+    """
+    import aiohttp
+    
+    api_key = api_key_data.get("api_key", "").strip()
+    
+    if not api_key:
+        return {
+            "valid": False,
+            "message": "API key is required"
+        }
+    
+    try:
+        # Test the API key with a simple configuration request
+        url = f"https://api.themoviedb.org/3/configuration?api_key={api_key}"
+        
+        timeout = aiohttp.ClientTimeout(total=10)
+        async with aiohttp.ClientSession() as session:
+            async with session.get(url, timeout=timeout) as response:
+                if response.status == 200:
+                    return {
+                        "valid": True,
+                        "message": "TMDB API key is valid"
+                    }
+                elif response.status == 401:
+                    return {
+                        "valid": False,
+                        "message": "Invalid API key"
+                    }
+                else:
+                    return {
+                        "valid": False,
+                        "message": f"TMDB API error: {response.status}"
+                    }
+    except aiohttp.ClientError as e:
+        return {
+            "valid": False,
+            "message": f"Connection error: {str(e)}"
+        }
+    except Exception as e:
+        return {
+            "valid": False,
+            "message": f"Validation error: {str(e)}"
+        }