Add scheduled tasks (#13470)

### What problem does this PR solve?

1. RAGFlow server will send heartbeat periodically.
2. This PR will including:
- Scheduled task
- API server message sending
- Admin server API to receive the message.

### Type of change

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

---------

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

internal/handler/user.go

@@ -164,7 +164,7 @@ func (h *UserHandler) LoginByEmail(c *gin.Context) {
 		return
 	}
 
-	user, code, err := h.userService.LoginByEmail(&req)
+	user, code, err := h.userService.LoginByEmail(&req, false)
 	if err != nil {
 		c.JSON(http.StatusOK, gin.H{
 			"code":    code,