refactor(keycloak): remove authentik naming and switch to keycloak-only paths

backend/app/schemas/idp_admin.py

@@ -0,0 +1,14 @@
+from pydantic import AliasChoices, BaseModel, Field
+
+
+class KeycloakEnsureUserRequest(BaseModel):
+    user_sub: str | None = Field(default=None, validation_alias=AliasChoices("user_sub", "sub"))
+    username: str | None = None
+    email: str
+    display_name: str | None = None
+    is_active: bool = True
+
+
+class KeycloakEnsureUserResponse(BaseModel):
+    idp_user_id: str
+    action: str