Add subscription link field to user model

- Add subscription_link column to users table (nullable, unique)
- Add SUBSCRIPTION_URL to config settings
- Update user creation to include subscription link from Remnawave
- Add support subscription ticket creation with formatted message
- Add "update link" button to main menu
- Refactor support subscription formatting to include user details

schemas/users.py

@@ -5,7 +5,8 @@ from typing import Optional
 @dataclass
 class NewUserDTO:
     id: int
-    referal: int
+    referal: Optional[int] = None
+    link: Optional[str] = None
 
 
 @dataclass