Chore: Add Offline Agent Runner for Local Testing

[AviJxn]

Summary
Adds a standalone utility script (tests/local_agent_runner.py) to simulate agent retrieval offline.

Why is this needed?

• Allows developers to test retrieval logic without requiring Google Cloud credentials.
• Serves as a foundation for future CI/CD integration.

Safety

• Zero impact on production code. All changes are isolated to the tests/ directory.
• No dependencies added to the main application.