Add token refresh handling for 401 responses across clients

- Implemented `RefreshTokens` method in client interfaces and Gemini clients.
- Updated handlers to call `RefreshTokens` on 401 responses and retry requests if token refresh succeeds.
- Enhanced error handling and retry logic to accommodate token refresh flow.

Update README to include Qwen login instructions

- Added Qwen OAuth login command instructions in both English and Chinese README files.
- Made minor updates to existing command examples for consistency.

internal/cmd/run.go

@@ -263,6 +263,7 @@ func StartService(cfg *config.Config, configPath string) {
 		for {
 			select {
 			case <-ctxRefresh.Done():
+				log.Debugf("refreshing tokens stopped...")
 				return
 			case <-ticker.C:
 				checkAndRefresh()