Covers the projects and settings journeys: registering a repo and what the sidebar then shows (re-adding is a no-op, a bogus path is refused with a reason), unknown projects degrading quietly, settings written in the dashboard reaching the next resumed session, and the usage panel's quota readings and sweep button.

## Before writing SPEC.md files

Read https://raw.githubusercontent.com/brillout/sdd/refs/heads/main/sdd.md
