First commit of §7 multi-repo ownership. A 'project' is a repo-root that
declaratively manages a slice of the shared group tree; each group node is
owned by exactly one project (single-owner-per-node). This lands the registry
+ shared types and wires the inert 0047 `owner_project` seam — no behavior
change yet (claim logic is the next commit).
- migration 0066: `projects` table (UUID pk, unique slug, name, created_by →
admin_users ON DELETE SET NULL); `groups.owner_project` gains its FK →
projects(id) ON DELETE SET NULL (un-claim, never cascade-destroy a tree) +
an index.
- shared: `ProjectId` (id_type! macro) + `Project` struct; `Group` gains
`owner_project: Option<ProjectId>`.
- group_repo: GROUP_COLS + the ancestors recursive-CTE term now carry
`owner_project`, so `ancestors()` surfaces ownership for the nearest-claimed
fold; GroupRow + From updated.
- schema snapshot re-blessed; /version schema assertion 65 → 66.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
