Thin CONTENT_ROOT content plane (ADR-0003/0004) with space visual field,
product UI for Title/Abstract/Visual, page list sidebar, and tests. Update
capability model and smoke checklist; mark WP-0006 finished.
Introduce tenant-scoped Space/SpaceMembership with list and detail views.
Document markdown-in-Forgejo as content SoR (ADR-0002). Run migrations on
container start so app.coulomb.social picks up the new tables.
