feat: enhance VLM response parsing and DOUBAO model support

- Fix JSON extraction logic by prioritizing brace counting method
- Add support for DOUBAO string array coordinate format
- Introduce IS_UI_TARS helper function for model type checking
- Add comprehensive tests for JSON parsing and coordinate handling
- Improve error handling with retry delays for LLM service failures

uixt/driver_ext_ai.go

@@ -50,6 +50,7 @@ func (dExt *XTDriver) StartToGoal(ctx context.Context, prompt string, opts ...op
 			if errors.Is(err, code.LLMRequestServiceError) {
 				log.Warn().Err(err).Int("attempt", attempt).
 					Msg("LLM service request failed, retrying...")
+				time.Sleep(5 * time.Second)
 				continue
 			}
 			// Create planning result with error