Wave 4 of replacing the fixed-data mock adapter, and the first capability the
mall never had a backend for: the home page's banners, promo tiles, quick links
and floor advert art move out of local arrays.
- four explicit tables (`banners`, `promos`, `quick_links`, `floor_adverts`)
rather than one JSONB payload table, so Postgres enforces each shape
- a migration seeds them from the assets the page already rendered, so the flip
is visually a no-op. Destinations are real routes now: the mock's promo links
pointed at dangling `?category=c1` ids and its first banner used `sort=sales`,
which the catalog API rejects
- `GET /api/content/home` is public and returns the four active, ordered lists,
always including a key so a page can render a missing block
- `GET /api/admin/content` and `PUT /api/admin/content/{kind}` let a platform
admin read everything and replace one kind transactionally, with positions
reindexed from the submitted order and a rejected list changing nothing
- the mall's fixed-data adapter learns `getHomeContent`, and a `content` domain
joins the per-domain switch so the rollback path still renders the page
Verified: 23 backend tests green including six new content tests; all three
frontends build; the home page renders the same four blocks as before, an admin
reorder and deactivation change the rendered carousel, and the fixed-data
rollback renders every block with the backend stopped.
OpenSpec change: openspec/changes/replace-mock-api-wave-4
