refactors

backend/schemas/meta.py

@@ -0,0 +1,16 @@
+from pydantic import BaseModel
+
+from models import BitcoinTransferMethod, InviteStatus, Permission
+
+
+class ConstantsResponse(BaseModel):
+    """Response model for shared constants.
+
+    Note: Using actual enum types ensures OpenAPI schema includes enum values,
+    allowing frontend type generation to produce matching TypeScript enums.
+    """
+
+    permissions: list[Permission]
+    roles: list[str]
+    invite_statuses: list[InviteStatus]
+    bitcoin_transfer_methods: list[BitcoinTransferMethod]