[Feature Request] Optional JWT Authentication middleware for session endpoints

Hi team! I've been exploring the Agent Starter Pack and really appreciate the production-ready experience it provides.

I noticed that the current scaffolding (particularly in adk_live and get_fast_api_app) exposes session-related endpoints without authentication by default.

While this makes local development simple, many users may deploy directly using make deploy. In those scenarios, it could be beneficial to have an optional authentication layer to prevent unintended access to sessions when exposed publicly.

Proposed Improvement:
I’d like to contribute an optional authentication middleware (e.g., JWT-based or Google Auth integration) that can be enabled via environment variable or configuration flag.

This would preserve the simplicity of local development while making production deployments more secure by default.

Would the maintainers be open to a Pull Request implementing this enhancement?