Add attendance id resp for event join api, set root api to /app/api/v1

Signed-off-by: Asai Neko <sugar@sne.moe>

docs/swagger.yaml

@@ -125,6 +125,11 @@ definitions:
       kyc_id:
         type: string
     type: object
+  service_event.EventJoinResponse:
+    properties:
+      attendance_id:
+        type: string
+    type: object
   service_kyc.KycQueryData:
     properties:
       kyc_id:
@@ -808,7 +813,7 @@ paths:
             - $ref: '#/definitions/utils.RespStatus'
             - properties:
                 data:
-                  type: object
+                  $ref: '#/definitions/service_event.EventJoinResponse'
               type: object
         "400":
           description: Invalid Input or UUID Parse Failed