feat: Redis cluster support + version auto-detect + metrics API

backend/internal/handler/instance_extra.go

@@ -20,9 +20,9 @@ func AccessibleInstances(c *gin.Context) {
 		// admin/dba see all instances, filter by access_mode if needed
 		query := model.DB.Order("id")
 		if accessType == "readonly" {
-			query = query.Where("access_mode IN ?", []string{"readwrite", "readonly"})
+			query = query.Where("access_mode IN ? OR access_mode IS NULL", []string{"readwrite", "readonly"})
 		} else {
-			query = query.Where("access_mode IN ?", []string{"readwrite", "write"})
+			query = query.Where("access_mode IN ? OR access_mode IS NULL", []string{"readwrite", "write"})
 		}
 		query.Find(&instances)
 	} else {
@@ -117,10 +117,11 @@ func TestNewConnection(c *gin.Context) {
 		instance.Database = &req.Database
 	}
 
-	success, message := testDBConnection(instance)
-	if success {
-		c.JSON(http.StatusOK, gin.H{"success": true, "message": message})
-	} else {
-		c.JSON(http.StatusBadRequest, gin.H{"success": false, "message": message})
-	}
+	result := testDBConnectionFull(instance)
+	c.JSON(http.StatusOK, gin.H{
+		"success":      result.Success,
+		"message":      result.Message,
+		"version":      result.Version,
+		"cluster_mode": result.ClusterMode,
+	})
 }