feat: Redis单值结果直接展示+JSON中文格式化+悬浮复制

1. GET/HGET/TTL等单值命令: 直接展示raw值, 不再套table
2. JSON自动检测+格式化(中文正常显示, 2空格缩进)
3. 非JSON值(如false/数字)直接文本展示
4. 代码块右上角悬浮复制按钮(hover显示)
5. 工具栏显示值类型(JSON/String)替代行列数

backend/internal/handler/instance_detail.go

@@ -14,6 +14,8 @@ import (
 	"sql-platform/internal/middleware"
 	"strings"
 	"strconv"
+	"encoding/json"
+	"bytes"
 )
 
 // GET /api/v1/instances/:id/detail/databases
@@ -703,24 +705,33 @@ func executeRedisQuery(instance *model.Instance, dbSelect string, command string
 			columns = []string{"field", "value"}
 		} else {
 			// Single value result (GET, HGET, TYPE, TTL, etc.)
-			// Try to extract key name from command
 			keyName := ""
 			if len(parts) > 1 {
 				keyName = parts[1]
 			}
-			if keyName != "" {
-				rows = append(rows, map[string]interface{}{
-					"key":   keyName,
-					"value": fmt.Sprintf("%v", v),
-				})
-				columns = []string{"key", "value"}
-			} else {
-				rows = append(rows, map[string]interface{}{
-					"command": command,
-					"result":  fmt.Sprintf("%v", v),
-				})
-				columns = []string{"command", "result"}
+			rawValue := fmt.Sprintf("%v", v)
+			// Try to pretty-format JSON with Chinese characters preserved
+			var prettyJSON string
+			var parsed interface{}
+			if json.Unmarshal([]byte(rawValue), &parsed) == nil {
+				switch parsed.(type) {
+				case map[string]interface{}, []interface{}:
+					var buf bytes.Buffer
+					enc := json.NewEncoder(&buf)
+					enc.SetEscapeHTML(false)
+					enc.SetIndent("", "  ")
+					enc.Encode(parsed)
+					prettyJSON = strings.TrimRight(buf.String(), "\n")
+				}
 			}
+			return gin.H{
+				"columns":   []string{},
+				"rows":      []interface{}{},
+				"total":     0,
+				"raw_value": prettyJSON != "",
+				"raw_key":   keyName,
+				"raw_text":  rawValue,
+			}, nil
 		}
 	}