fix(provider): set category to custom for imported default config

Ensure that when importing default configuration from live files,
the created provider is properly marked with category "custom" for
correct UI display and filtering.

src-tauri/src/services/provider.rs

@@ -532,12 +532,13 @@ impl ProviderService {
             }
         };
 
-        let provider = Provider::with_id(
+        let mut provider = Provider::with_id(
             "default".to_string(),
             "default".to_string(),
             settings_config,
             None,
         );
+        provider.category = Some("custom".to_string());
 
         {
             let mut config = state.config.write().map_err(AppError::from)?;