willchen96 makes OpenAI a first-class option in Mike

A third AI provider lands, and the settings screen finally tells users which keys the server is in charge of.

willchen96 added OpenAI alongside the Claude and Gemini engines that Mike already supports, wiring it through both the backend's streaming pipeline and the chat UI where users pick a model. Nothing exotic - the point is that legal teams running this fork now have a real choice of three frontier providers rather than two.

The nicer detail is around keys. The settings screen now distinguishes keys a user typed into the browser from keys the server is reading out of its own environment, and locks the in-browser fields when the server is the source of truth. Server-set keys win. The same pass tightened the default database permissions so the public-facing client can't reach backend-owned tables directly, and tidied up the account and project screens.