feat(ui): explicit Deny semantics with 2-denial hard-filter escalation (Sprint 8)

User policy decision (2026-06-05, exact): 'Hard filter. If it is denied
this week twice, it should be considered denied for good.'

The planner had no cross-week memory of denials: a denial on
meal_plan_item.approval_status was never consulted by the planner,
and NeverSuggest (the per-family permanent blocklist) was empty for
the user. The 'Roasted Sweet Potato and Chickpea Bowl' the user
denied on 2026-05-15 was still in the planner's pool 3 weeks
later.

Implements C + Z (explicit two-button model + soft-decay +
hard-filter escalation):
- Approve: untouched.
- Deny this week (1st in 90d): denial_expires_at = now() + 90d.
- Deny this week (2nd in 90d, server-side auto-escalation):
  denial_expires_at = NULL + a NeverSuggest row written.
- Never again (explicit): same as the 2nd-time auto-escalation.

Both soft and permanent denials are hard filters in the planner
(per user). A denied recipe never reappears until either the 90d
window expires or the user un-blocks via the NeverSuggest API.

Changes:
- Migration 0016: meal_plan_item.denial_expires_at (partial index)
  and meal_plan_vote.denial_scope.
- 3 backend helpers (_apply_denial, _ensure_never_suggest_recipe,
  _has_prior_active_soft_denial) — single source of truth for the
  deny path.
- POST /api/meals/items/{id}/deny?scope=this_week|never_again
  (default this_week). Returns promoted_to_permanent.
- POST /api/meals/vote/{id} extended: vote=approve|deny|never_again.
  Returns denial_scope + promoted_to_permanent.
- GET /api/meals/vote/{id} HTML page renders 3 buttons; supports
  one-click ?scope=... for email direct-action links.
- Email template (step_email): 3 direct-action links per recipe
  plus a secondary 'open vote page' link.
- Planner: _load_blocklists returns 3 sets; soft_denied_recipes
  is hard-filtered (union with blocked_recipes at the call site).
- Frontend: MealCard renders 3 buttons (Approve / Deny this week
  / Never again) for pending items. handleDeny is scope-aware;
  toast reflects promoted_to_permanent. window.confirm on
  'Never again' prevents accidental permanent blocks.

Verification:
- npm run build green.
- 21/21 planner tests pass (1 pre-existing test_filter_blocks_by_cost
  failure is NOT introduced by Sprint 8 — verified via git stash).
- Review/sprint8-verification.md: 11-step browser smoke + 4 API
  curls + email-render procedure + rollback.

Files:
- backend/alembic/versions/0016_denial_decay_and_scope.py (new)
- backend/app/models/__init__.py:221-242, 250-269
- backend/app/schemas/__init__.py:204-219, 248-269
- backend/app/api/meals.py:30-138 (helpers), 240-330 (HTML page),
  380-455 (submit_vote), 486-552 (deny_meal_item)
- backend/app/services/orchestrator/steps.py:283-300
- backend/app/services/planner/generate.py:59-99, 150-194
- frontend/src/api/index.ts:48-58
- frontend/src/pages/Dashboard.tsx:38-50, 385-410
- Review/{sprint8-verification,ui-nielsen-audit,handoff-ui-audit}.md
- fix-ui-audit.md
- docs/HANDOFF.md
- .agent/{plan,context}.md

Deploy (user runs on deployment host):
  cd ~/MealPlanner && git pull
  docker compose exec backend alembic upgrade head
  docker compose -f docker-compose.yml up -d --build backend frontend

Review/handoff-ui-audit.md

@@ -2,7 +2,30 @@
 
 You are taking over a 6-sprint UI/UX audit and fix cycle. All code changes are committed and build green. The user's deployment host (Tailscale `100.108.224.12`) is the only environment you should touch for verification — the local repo on this machine (`/home/peter/Projects/MealPlanner`) was the editing host; the running app lives elsewhere.
 
-**Date of handoff: 2026-06-04. Last updated: 2026-06-05 (Sprint 7 in progress).**
+**Date of handoff: 2026-06-04. Last updated: 2026-06-05 (Sprint 8 in progress).**
+
+---
+
+## ⚠️ Active sprint: Sprint 8 — "Deny" semantics (C + Z, hard-filter escalation)
+
+**Status: in progress. User approved on 2026-06-05. Code not yet committed.**
+
+**User policy decision (2026-06-05, exact words):** "Hard filter. If it is denied this week twice, it should be considered denied for good."
+
+**Root cause (one-liner):** the planner has no cross-week memory of denials. Denials live on the `meal_plan_item` row, are never consulted by the planner, and the `NeverSuggest` blocklist is empty for the user's family. The user's "Roasted Sweet Potato and Chickpea Bowl" was denied on 2026-05-15 but the recipe was still in the pool for the next 90+ days.
+
+**Policy (Sprint 8):**
+
+- "Approve" → `item.approval_status = approved`. n/a.
+- "Deny this week" (1st in 90d) → `denied` + `denial_expires_at = now() + 90d`. Recipe becomes eligible again after 90d.
+- "Deny this week" (2nd in 90d — **server-side auto-escalation**) → `denied` + `denial_expires_at = NULL` + a `NeverSuggest` row written. Permanent.
+- "Never again" (explicit) → same as the 2nd-time auto-escalation. Permanent.
+
+**Scope (12 boxes):** see `.agent/plan.md` "Active sprint" section. Code changes are M-L: 1 migration, 2 model columns, 2 schema fields, 3 backend helpers, 2 endpoint extensions, 1 planner update, 1 email template update, 1 webui MealCard update. **No new dependencies. Migration 0016 required.**
+
+**Tracking docs:** `Review/sprint8-verification.md` (deploy + smoke), `Review/ui-nielsen-audit.md` Sprint 8 status block, `fix-ui-audit.md` T2.1–T2.10, `Review/handoff-ui-audit.md` (this file), `docs/HANDOFF.md` Sprint 8 section.
+
+**Thread 3 (§Future backlog) is deferred** until S8 is deployed + verified. F1 onboarding, F8/F9 proposals, dead `Generate Meal Plan` CTA at `Dashboard.tsx:415`.
 
 ---
 
@@ -278,4 +301,4 @@ cd frontend && npm run build
 
 Trust the build output. Trust the smoke checklist. Don't trust the deployment host's UI until the user confirms. The verification model is "I shipped, you verified, you reported, I fixed" — the agent in this role never sees the live UI directly.
 
-**Last updated: 2026-06-05** — Sprints 1, 2, 3, 4, 5, 6 deployed-or-awaiting-deploy; **Sprint 7 (webui empty-meal-plan fix) in progress**. See the "Active sprint" callout at the top of this file for the current state.
+**Last updated: 2026-06-05** — Sprints 1, 2, 3, 4, 5, 6 deployed-or-awaiting-deploy; Sprint 7 (webui empty-meal-plan fix) **committed `09c7525` awaiting user deploy**; **Sprint 8 (Deny semantics C + Z with hard-filter escalation) in progress**. See the "Active sprint" callout at the top of this file for the current state.