Implement Search() in Infinity in GO (#13645)

### What problem does this PR solve?

Implement Search() in Infinity in GO.

The function can handle the following request. 
"search '曹操' on datasets 'infinity'" 
"search '常胜将军' on datasets 'infinity'"
"search '卓越儒雅' on datasets 'infinity'"
"search '辅佐刘禅北伐中原' on datasets 'infinity'"

The output is exactly the same as  request to python Search()

### Type of change

- [ ] New Feature (non-breaking change which adds functionality)

internal/cli/client.go

@@ -31,9 +31,9 @@ type PasswordPromptFunc func(prompt string) (string, error)
 
 // RAGFlowClient handles API interactions with the RAGFlow server
 type RAGFlowClient struct {
-	HTTPClient        *HTTPClient
-	ServerType        string           // "admin" or "user"
-	PasswordPrompt    PasswordPromptFunc // Function for password input
+	HTTPClient     *HTTPClient
+	ServerType     string             // "admin" or "user"
+	PasswordPrompt PasswordPromptFunc // Function for password input
 }
 
 // NewRAGFlowClient creates a new RAGFlow client
@@ -489,6 +489,28 @@ func (c *RAGFlowClient) getDatasetID(datasetName string) (string, error) {
 	return "", fmt.Errorf("dataset '%s' not found", datasetName)
 }
 
+// formatEmptyArray converts empty arrays to "[]" string
+func formatEmptyArray(v interface{}) string {
+	if v == nil {
+		return "[]"
+	}
+	switch val := v.(type) {
+	case []interface{}:
+		if len(val) == 0 {
+			return "[]"
+		}
+	case []string:
+		if len(val) == 0 {
+			return "[]"
+		}
+	case []int:
+		if len(val) == 0 {
+			return "[]"
+		}
+	}
+	return fmt.Sprintf("%v", v)
+}
+
 // SearchOnDatasets searches for chunks in specified datasets
 // Returns (result_map, error) - result_map is non-nil for benchmark mode
 func (c *RAGFlowClient) SearchOnDatasets(cmd *Command) (map[string]interface{}, error) {
@@ -582,6 +604,22 @@ func (c *RAGFlowClient) SearchOnDatasets(cmd *Command) (map[string]interface{},
 				"term_similarity":   chunkMap["term_similarity"],
 				"vector_similarity": chunkMap["vector_similarity"],
 			}
+			// Add optional fields that may be empty arrays
+			if v, ok := chunkMap["doc_type_kwd"]; ok {
+				row["doc_type_kwd"] = formatEmptyArray(v)
+			}
+			if v, ok := chunkMap["important_kwd"]; ok {
+				row["important_kwd"] = formatEmptyArray(v)
+			}
+			if v, ok := chunkMap["mom_id"]; ok {
+				row["mom_id"] = formatEmptyArray(v)
+			}
+			if v, ok := chunkMap["positions"]; ok {
+				row["positions"] = formatEmptyArray(v)
+			}
+			if v, ok := chunkMap["content_ltks"]; ok {
+				row["content_ltks"] = v
+			}
 			tableData = append(tableData, row)
 		}
 	}