refactor: rename idp fields to provider naming

backend/app/schemas/idp_admin.py

@@ -1,7 +1,7 @@
 from pydantic import AliasChoices, BaseModel, Field
 
 
-class KeycloakEnsureUserRequest(BaseModel):
+class ProviderEnsureUserRequest(BaseModel):
     user_sub: str | None = Field(default=None, validation_alias=AliasChoices("user_sub", "sub"))
     username: str | None = None
     email: str
@@ -9,6 +9,6 @@ class KeycloakEnsureUserRequest(BaseModel):
     is_active: bool = True
 
 
-class KeycloakEnsureUserResponse(BaseModel):
-    idp_user_id: str
+class ProviderEnsureUserResponse(BaseModel):
+    provider_user_id: str
     action: str