feat(ui): Sprint 10 — Deny Forever on Recipes (card overlay + detail button + undo toast)

User-driven follow-up to Sprint 8: surface the Sprint 1-3 NeverSuggest
infrastructure on the Recipes surface so a family can pre-emptively
mark a recipe as never-suggest before it appears in a plan.

Backend (3 changes):
- POST /api/never-suggest (public, webui-facing). Idempotent on
  (family, recipe, reason). Returns the row joined with recipe_name.
- DELETE /api/never-suggest/{ns_id} (public, webui-facing). Row-level
  ownership check (403 if cross-family), 404 if absent.
- NeverSuggestRead.recipe_name + .ingredient_name server-side joins
  via _attach_names() helper (one LEFT OUTER JOIN per kind).
- Admin path (POST/DELETE /api/admin/never-suggest) unchanged.

Frontend (4 changes):
- New NeverSuggestButton component (~290 lines). Two variants: card
  (overlay on RecipeCard) and detail (text buttons in RecipeDetail
  top bar). Popover with Allergy (red, window.confirm) + Dislike
  (neutral, no confirm). Undo toast via showToast.undo() (Sprint 3
  B12 pattern, 6s window). Pre-existing block detection shows a
  Blocked state with an Unblock path.
- mealPlannerApi.neverSuggest.list/add/remove in api/index.ts.
- Recipes.tsx overlay: RecipeCard has position: relative; button is
  opacity-0 group-hover:opacity-100 focus:opacity-100. e.preventDefault
  + e.stopPropagation prevents accidental navigation.
- RecipeDetail.tsx top bar: new Deny forever button group to the left
  of Add to Plan.

Build: npm run build green (tsc 0 errors, vite 0 errors) on
docker-willester. Bundle 487 -> 495 kB. No new dependencies. No
migration (NeverSuggest table exists from prior sprints).

Tracking: Review/sprint10-verification.md (9-step browser smoke +
5 API curls + undo test + a11y check).

backend/app/schemas/never_suggest.py

@@ -28,5 +28,12 @@ class NeverSuggestRead(BaseModel):
     recipe_id: Optional[UUID] = None
     reason: Optional[str] = None
     notes: Optional[str] = None
+    # Server-side joins. Populated by the router via a single LEFT OUTER
+    # JOIN to recipe / ingredient; falls back to None when the target
+    # row has been deleted (the FK is ON DELETE CASCADE so the
+    # NeverSuggest row goes with it; this is belt-and-suspenders for
+    # the rare in-flight case).
+    recipe_name: Optional[str] = None
+    ingredient_name: Optional[str] = None
 
     model_config = {"from_attributes": True}