Enhance AgentDriver with caching and pipeline operations discovery

[martintb]

This pull request introduces a robust caching and error-reporting system for pipeline operation (PipelineOp) discovery in AFL.double_agent.AgentDriver, along with improvements to the frontend pipeline builder UI to display warnings and optimize loading. It also adds targeted tests for the new backend logic. The changes improve performance, reliability, and user feedback when loading available pipeline operations.

Backend: PipelineOp discovery, caching, and error handling

• Refactored PipelineOp discovery to support in-memory and disk caching, using a signature based on module file metadata to detect changes. Added a strict mode to bypass caches and raise errors on discovery failures. [1] [2] [3]
• Added detailed warning collection for errors during module import, inspection, or metadata extraction, and exposed these warnings in the API response. [1] [2]
• Added a strict flag to the pipeline_ops driver method, allowing clients to request strict error handling.
• Added a suite of tests for the new caching and strict mode logic, including memory cache, disk cache, and strict mode behaviors.

Frontend: Pipeline builder UI improvements

• Updated the frontend JS to handle the new backend response format, displaying warnings to users if any occurred during PipelineOp discovery.
• Optimized app initialization by loading operations in parallel with other resources and showing the UI as soon as the core pipeline state is ready, improving perceived performance.- Introduced caching mechanisms for pipeline operations using memory and disk.