fix(migration): simplify aisle migration + add persistent backup script

- Drop the empty batch_alter_table block and the meaningless
  set_config call from migration 0015. Temp tables still persist
  for the migration's session (Alembic's transactional_ddl).
- New backend/scripts/persist_aisle_backup.sql creates
  public.ingredient_aisle_backup_0015 and
  public.grocery_item_aisle_backup_0015 permanent tables for
  operators who want a recoverable record beyond the migration.
- Update Review/sprint2-verification.md, Review/ui-nielsen-audit.md
  and fix-ui-audit.md with the correct container-based deploy
  steps: docker compose exec db psql -U mealplanner -d mealplanner
  -f /dev/stdin < ...sql. Host psql is not available on the
  deployment host; the db runs inside the container.

Review/sprint2-verification.md

@@ -18,24 +18,43 @@
 | `frontend/src/pages/ShoppingList.tsx` | B9: `AISLE_LABEL` map + `aisleDisplay()`; S3.3: 3-col grid on all viewports with compact mobile sizing. |
 | `frontend/src/pages/Recipes.tsx` | B11: `applied`/`pending` filter state, Apply/Reset buttons, active-count chip on Filters button, `role="region"`. |
 
-## How to verify on the deployment host
+## How to deploy on the remote host (the database is in a container)
+
+The dev DB runs inside `mealplanner-db-1`. No host `psql` is required. All commands run via `docker compose exec` from the project root.
 
 ```bash
-cd /path/to/MealPlanner
+cd ~/MealPlanner
 git pull
 
-# 1. Backend migration (one-off, dry-run first)
-psql "$DATABASE_URL" -f backend/scripts/dry_run_aisle_migration.sql
-docker compose exec backend alembic upgrade head
+# 1. (Optional but strongly recommended) Take a persistent backup of
+#    aisle values BEFORE the migration runs. This stays in the DB
+#    even after the migration session ends.
+docker compose exec -T db psql -U mealplanner -d mealplanner \
+  -f /dev/stdin < backend/scripts/persist_aisle_backup.sql
 
-# 2. Frontend rebuild + restart
+# 2. Dry-run preview — counts rows that would change, no writes.
+docker compose exec -T db psql -U mealplanner -d mealplanner \
+  -f /dev/stdin < backend/scripts/dry_run_aisle_migration.sql
+# Expected output (example):
+#       tbl      | rows_to_change | distinct_old_values
+#  --------------+----------------+---------------------
+#   grocery_item |          10539 |                  16
+#   ingredient   |          10657 |                  27
+
+# 3. If the dry-run row counts look sane, apply the migration:
+docker compose exec backend alembic upgrade head
+# Expected: "Running upgrade 0014 -> 0015, normalize_pantry_aisles"
+
+# 4. Frontend rebuild + restart (Sprint 2 UI changes are already merged).
 docker compose -f docker-compose.yml up -d --build frontend
 
-# 3. Smoke-check the live site
+# 5. Smoke-check the live site
 curl -s -o /dev/null -w "%{http_code}\n" http://100.108.208.56:8082/
 # Expect: 200
 ```
 
+If the dry-run row count is high (>1k on ingredient) and you want to inspect what would change before applying, uncomment the second query at the bottom of `dry_run_aisle_migration.sql` and re-run.
+
 ## Manual smoke checks
 
 - `/` (mobile 390 px): Generate button visible on every empty slot; new meal title clamps to 2 lines without `B..`.