Fix broken tests, add thread-safe OpenAI client, document codebase architecture#13

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Copilot wants to merge 3 commits intomainfrom

copilot/explore-and-understand-code

Commits on Dec 1, 2025

Initial plan
Copilot
committed
Fix broken tests, lazy-load OpenAI client, and add comprehensive project documentation

Copilot
and
yigagilbert
committed
Address code review feedback: thread-safe OpenAI client, clearer mock paths, improved documentation

Copilot
and
yigagilbert
committed