juanjo rips Mike off Supabase and onto a self-hostable stack

This change set replaces Supabase - the hosted database and login service Mike previously leaned on - with a fully local stack. Postgres runs in a container, Auth.js handles sign-in with a cookie-based bridge to the backend, and Drizzle (a tool that defines the database shape in code) becomes the single source of truth for tables like users, projects, documents, workflows and chat messages. A companion change swaps the previously hard-coded Cloudflare R2 file store for a provider-agnostic layer, with MinIO standing in locally so uploads, downloads and deletes work the moment the stack comes up.

For anyone evaluating Mike, the practical effect is that a developer or vendor can now stand the whole thing up on a laptop or a private server without signing contracts with Supabase or Cloudflare first. juanjo also shipped architecture decision records and runbooks alongside the code, which is unusually disciplined for a fork at this stage.