fix: resolve pylint and type-checking issues

- Fix return type annotation in SetupRedirectMiddleware.dispatch() to use Response instead of RedirectResponse
- Replace broad 'except Exception' with specific exception types (FileNotFoundError, ValueError, OSError, etc.)
- Rename AppConfig.validate() to validate_config() to avoid shadowing BaseModel.validate()
- Fix ValidationResult.errors field to use List[str] with default_factory
- Add pylint disable comments for intentional broad exception catches during shutdown
- Rename lifespan parameter to _application to indicate unused variable
- Update all callers to use new validate_config() method name

src/server/services/config_service.py

@@ -90,7 +90,7 @@ class ConfigService:
             config = AppConfig(**data)
             
             # Validate configuration
-            validation = config.validate()
+            validation = config.validate_config()
             if not validation.valid:
                 errors = ', '.join(validation.errors or [])
                 raise ConfigValidationError(
@@ -123,7 +123,7 @@ class ConfigService:
             ConfigValidationError: If config validation fails
         """
         # Validate before saving
-        validation = config.validate()
+        validation = config.validate_config()
         if not validation.valid:
             errors = ', '.join(validation.errors or [])
             raise ConfigValidationError(
@@ -180,7 +180,7 @@ class ConfigService:
         Returns:
             ValidationResult: Validation result with errors if any
         """
-        return config.validate()
+        return config.validate_config()
     
     def create_backup(self, name: Optional[str] = None) -> Path:
         """Create backup of current configuration.