add default entries creation on post-migrate signal and refactor application model logic

app_gateway/caddy_config_export.py

@@ -2,14 +2,12 @@ import json
 import os
 
 from app_gateway.models import (
-    AccessPolicy, Application, ApplicationPolicy
+    AccessPolicy, Application, ApplicationPolicy, RESERVED_APP_NAME
 )
 from gatekeeper.models import (
     AuthMethod, GatekeeperGroup, GatekeeperIPAddress, GatekeeperUser
 )
 
-RESERVED_APP_NAME = 'wireguard_webadmin'
-
 POLICY_TYPE_MAP = {
     'public': 'bypass',
     'protected': 'protected',