feat(ocr): 支持 PP-OCRv6 异步识别模型并设为默认，解决排队与高延迟问题

backend/internal/modules/chat/qrcode_ocr.go

@@ -443,6 +443,7 @@ func (r *Repository) submitPaddleOCRJob(ctx context.Context, config *QrCodeOCRCo
 	optionalPayload, _ := json.Marshal(map[string]bool{
 		"useDocOrientationClassify": false,
 		"useDocUnwarping":           false,
+		"useTextlineOrientation":    false,
 		"useChartRecognition":       false,
 	})
 	_ = writer.WriteField("optionalPayload", string(optionalPayload))
@@ -790,13 +791,25 @@ func collectPaddleOCRText(value any, texts *[]string) {
 			collectPaddleOCRText(item, texts)
 		}
 	case map[string]any:
+		// PP-OCRv6: prunedResult.rec_texts 包含检测并识别的文字列表
+		if recTexts, ok := v["rec_texts"].([]any); ok {
+			for _, item := range recTexts {
+				if text, ok := item.(string); ok && strings.TrimSpace(text) != "" {
+					*texts = append(*texts, text)
+				}
+			}
+			return
+		}
+		// PaddleOCR-VL: markdown.text 包含识别文本
 		if markdown, ok := v["markdown"].(map[string]any); ok {
 			if text, ok := markdown["text"].(string); ok && strings.TrimSpace(text) != "" {
 				*texts = append(*texts, text)
 			}
 		}
 		for key, item := range v {
-			if key == "images" || key == "outputImages" {
+			if key == "images" || key == "outputImages" || key == "ocrImage" || key == "inputImage" ||
+				key == "preprocessedImages" || key == "model_settings" || key == "text_det_params" ||
+				key == "logId" || key == "errorCode" || key == "errorMsg" || key == "dataInfo" {
 				continue
 			}
 			collectPaddleOCRText(item, texts)