docs: Sprint 15 round 3 — +10 recipes, library at 77 total

Sprint 15 round 3 (no new code; reused scripts/seed_recipes.py
from round 1, idempotent) added 10 more Spoonacular recipes to
the local library. 37 duplicates were skipped. Imports: 2
Asian leftovers (pho, kung pao) + 8 American comfort dishes
(chili, meatloaf, mac and cheese, BBQ chicken, pot roast,
shepherd pie, chicken pot pie, beef stew).

DB went 67 -> 77 total recipes (47 Spoonacular + 30 manual).
LLM test (Sprint 13, week 2026-08-03, prompt "comfort food,
no repeats from past 2 weeks"):
  {picked_count: 0, filled_count: 21, failed_count: 0}
21/21 slots filled, 0 failed.

All 6 running docs updated: plan.md (S15R3.1-S15R3.2),
context.md (D11-D13), sprint15-verification.md (round 3
section + 3-round summary table), ui-nielsen-audit.md
(round 3 paragraph), fix-ui-audit.md (T8.7), handoff-ui-
audit.md (TL;DR + Sprint 15 section), HANDOFF.md (round 3
paragraph + Last-updated footer).

Cumulative Sprint 15 work: 46 new Spoonacular recipes across
3 rounds. Library at 77 total — well past the 4-week coverage
threshold.

Review/ui-nielsen-audit.md

@@ -155,6 +155,8 @@ The app looks polished on the surface (Tailwind palette, clean cards, working to
 >
 > **Sprint 15 Round 2 (2026-06-07):** +18 recipes, library at 67 total. `scripts/seed_recipes_round2.py` (NEW, ~120 lines) — 50-query list focused on cuisines the round 1 list didn't cover: Indian (8) + Thai (6) + Chinese regional (6) + Soups & stews (6) + Salads (6) + Sandwiches/wraps (5) + Breakfast (5) + German/European (4) + French (4). Same idempotent behavior (409 on duplicate). 18 imported; 12 queries returned no hits from Spoonacular's free-tier index; 30th query hit 402. LLM test (Sprint 13, week 2026-07-20, prompt "variety, mix of cuisines, family-friendly, no repeats"): `picked_count=0 / filled_count=21 / failed_count=0`. **Library now covers all 21 slots of a week.** Tracking: appended to `Review/sprint15-verification.md`.
 >
+> **Sprint 15 Round 3 (2026-06-07):** +10 recipes, library at 77 total. Re-ran `scripts/seed_recipes.py` (round 1's script, idempotent) after the 50-pt quota rolled over. Skipped 37 duplicates; 10 new imports (Asian leftovers from round 1's cap-blocked queries + 8 American comfort dishes: Superbowl Chili, Veggie Meatloaf, Crab Mac and Cheese, BBQ Chicken, Classic Pot Roast, Lean Shepherd's Pie, Amazing Chicken Pot Pie, Slow Cooker Beef Stew). LLM test (Sprint 13, week 2026-08-03, prompt "comfort food, no repeats from past 2 weeks"): `picked_count=0 / filled_count=21 / failed_count=0`. **Library at 77, well past the 4-week coverage threshold.** Tracking: appended to `Review/sprint15-verification.md`.
+>
 >
 > **Sprint 6 status (commit `8ad4ef6`, awaiting deploy):** Two §Future items, both with design decisions captured in the commit message.
 > - **F3** Bulk 'add checked to pantry' on ShoppingList. Backend `POST /api/pantry/bulk` accepts `{items: HomePantryCreate[]}` and returns per-item status (`added` / `updated` / `skipped`) with totals. Per-item failure model: unknown ingredient → `skipped` with reason, not a 4xx. Frontend ShoppingList gains a primary `Add N to pantry` button next to the existing Reset button; toast reports `added X, updated Y, skipped Z`; only the items that actually landed are removed from the checked Set. **Scope decision:** ShoppingList only (the checked Set was the natural substrate; Pantry would need new multi-select UI).