feat(ai): add model list fetching in settings (#364)

- Add `ai_list_models` Tauri command and core support for fetching available models from OpenAI-compatible, Claude, and Ollama providers
- Replace manual model ID input with SearchableSelect in EditorSettingsDialog, including refresh button and loading state
- Add i18n translations for model list UI (en, es, zh-CN)
- Add tests for settings dialog layout and web driver management

src-tauri/src/lib.rs

@@ -175,6 +175,7 @@ pub fn run() {
             commands::ai::ai_stream,
             commands::ai::ai_cancel_stream,
             commands::ai::ai_test_connection,
+            commands::ai::ai_list_models,
             commands::ai::save_ai_config,
             commands::ai::load_ai_config,
             commands::ai::save_ai_conversation,