refactor: align backend with company-site-member schema and system-level RBAC groups

backend/app/schemas/permissions.py

@@ -7,7 +7,8 @@ class PermissionGrantRequest(BaseModel):
     display_name: str | None = None
     scope_type: str
     scope_id: str
-    module: str
+    system: str
+    module: str | None = None
     action: str
 
 
@@ -15,13 +16,15 @@ class PermissionRevokeRequest(BaseModel):
     authentik_sub: str
     scope_type: str
     scope_id: str
-    module: str
+    system: str
+    module: str | None = None
     action: str
 
 
 class PermissionItem(BaseModel):
     scope_type: str
     scope_id: str
+    system: str | None = None
     module: str
     action: str