feat: Add url field to PaginatedResponse and populate it using route path

Resolves: https://github.com/meta-llama/llama-stack/issues/1847
Changes:
- responses.py: added optional `url` field to PaginatedResponse
- server.py: automatically populate the URL field with route path

llama_stack/distribution/server/server.py

@@ -30,6 +30,7 @@ from fastapi.responses import JSONResponse, StreamingResponse
 from openai import BadRequestError
 from pydantic import BaseModel, ValidationError
 
+from llama_stack.apis.common.responses import PaginatedResponse
 from llama_stack.distribution.datatypes import AuthenticationRequiredError, LoggingConfig, StackRunConfig
 from llama_stack.distribution.distribution import builtin_automatically_routed_apis
 from llama_stack.distribution.request_headers import PROVIDER_DATA_VAR, User, request_provider_data_context
@@ -230,7 +231,10 @@ def create_dynamic_typed_route(func: Any, method: str, route: str) -> Callable:
                     return StreamingResponse(gen, media_type="text/event-stream")
                 else:
                     value = func(**kwargs)
-                    return await maybe_await(value)
+                    result = await maybe_await(value)
+                    if isinstance(result, PaginatedResponse) and result.url is None:
+                        result.url = route
+                    return result
             except Exception as e:
                 logger.exception(f"Error executing endpoint {route=} {method=}")
                 raise translate_exception(e) from e