Go: Add admin server status checking (#13571)

### What problem does this PR solve?

RAGFlow server isn't available when admin server isn't connected.

### Type of change

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

---------

Signed-off-by: Jin Hai <haijin.chn@gmail.com>

internal/handler/auth.go

@@ -17,8 +17,11 @@
 package handler
 
 import (
+	"fmt"
 	"net/http"
 	"ragflow/internal/common"
+	"ragflow/internal/logger"
+	"ragflow/internal/server/local"
 	"ragflow/internal/service"
 
 	"github.com/gin-gonic/gin"
@@ -69,13 +72,21 @@ func (h *AuthHandler) AuthMiddleware() gin.HandlerFunc {
 			return
 		}
 
+		if !local.IsAdminAvailable() {
+			license := local.GetAdminStatus()
+			errMsg := fmt.Sprintf("server license %s, check admin server status", license.Reason)
+			logger.Warn(errMsg)
+			c.JSON(http.StatusServiceUnavailable, gin.H{
+				"code":    common.CodeUnauthorized,
+				"message": errMsg,
+				"data":    "No",
+			})
+			return
+		}
+
 		c.Set("user", user)
 		c.Set("user_id", user.ID)
 		c.Set("email", user.Email)
 		c.Next()
 	}
 }
-
-func (h *AuthHandler) LoginByEmail1(c *gin.Context) {
-	println("hello")
-}