feat(mangas): per-field sort options + direction toggle on the catalog (0.88.0)

Sort the manga catalog by created / updated / title / author with an
independent asc/desc direction control. An omitted `order` defaults per field
(dates newest-first, text A→Z), matching the UI, so a bare `?sort=<field>`
means the same thing in the browser and over the API; `sort=recent` remains a
back-compat alias for `created`.

- Backend: SortField/SortOrder parsed with validation (structured 422 on bad
  input), per-field default_order, NULLS LAST only on the nullable author key,
  and migration 0033 indexing mangas(updated_at DESC, id) to back the default
  sort and its id tie-break.
- Frontend: catalog sort field + direction (SegmentedControl) on desktop and a
  mobile bottom sheet; pure helpers in $lib/mangaSort; keyboard-accessible
  direction control; visible Direction labels and a sheet "Done" button.
- Tests: backend integration coverage (defaults, alias, invalid input,
  ascending-id tie-break), frontend unit + e2e.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

README.md

@@ -81,7 +81,7 @@ Everything is namespaced under `/api/v1/`. `/api/*` outside the version prefix i
 | Method | Path                                                    | Description                                |
 | ------ | ------------------------------------------------------- | ------------------------------------------ |
 | GET    | `/api/v1/health`                                        | Liveness probe.                            |
-| GET    | `/api/v1/mangas?search=&sort=recent|title&limit=&offset=` | List/search mangas. Trigram fuzzy search.  |
+| GET    | `/api/v1/mangas?search=&sort=created\|updated\|title\|author&order=asc\|desc&limit=&offset=` | List/search mangas. Trigram fuzzy search. `sort` defaults to `updated`; `order` defaults per field (dates `desc`, text `asc`). `sort=recent` is a back-compat alias for `created`. |
 | GET    | `/api/v1/mangas/{id}`                                   | Single manga.                              |
 | GET    | `/api/v1/mangas/{id}/chapters`                          | Paginated chapter list, ordered by number. |
 | GET    | `/api/v1/mangas/{id}/chapters/{n}`                      | Single chapter.                            |