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)

tests/unit/test_config_models.py

@@ -4,6 +4,7 @@ from src.server.models.config import (
     AppConfig,
     ConfigUpdate,
     LoggingConfig,
+    NFOConfig,
     SchedulerConfig,
     ValidationResult,
 )
@@ -53,3 +54,56 @@ def test_backup_and_validation():
     res2 = cfg.validate_config()
     assert res2.valid is False
     assert any("backup.path" in e for e in res2.errors)
+
+
+def test_nfo_config_defaults():
+    """Test NFO configuration defaults."""
+    nfo = NFOConfig()
+    assert nfo.tmdb_api_key is None
+    assert nfo.auto_create is False
+    assert nfo.update_on_scan is False
+    assert nfo.download_poster is True
+    assert nfo.download_logo is True
+    assert nfo.download_fanart is True
+    assert nfo.image_size == "original"
+
+
+def test_nfo_config_image_size_validation():
+    """Test NFO image size validation."""
+    # Valid sizes
+    nfo1 = NFOConfig(image_size="original")
+    assert nfo1.image_size == "original"
+    
+    nfo2 = NFOConfig(image_size="w500")
+    assert nfo2.image_size == "w500"
+    
+    # Invalid size
+    with pytest.raises(ValueError, match="invalid image size"):
+        NFOConfig(image_size="invalid")
+
+
+def test_appconfig_includes_nfo():
+    """Test that AppConfig includes NFO configuration."""
+    cfg = AppConfig()
+    assert cfg.nfo is not None
+    assert isinstance(cfg.nfo, NFOConfig)
+    assert cfg.nfo.auto_create is False
+
+
+def test_config_update_with_nfo():
+    """Test ConfigUpdate can update NFO settings."""
+    base = AppConfig()
+    
+    # Create NFO config update
+    nfo_config = NFOConfig(
+        tmdb_api_key="test_key_123",
+        auto_create=True,
+        image_size="w500"
+    )
+    
+    upd = ConfigUpdate(nfo=nfo_config)
+    new = upd.apply_to(base)
+    
+    assert new.nfo.tmdb_api_key == "test_key_123"
+    assert new.nfo.auto_create is True
+    assert new.nfo.image_size == "w500"