Add draft_week skill v1

Drafts a week of seven dinners, Monday to Sunday, from a candidate pool
of Regulars and Quest log dinners, per CTXD PROMPTS.MD §3. Validators
require the seven dates of the week in order, every dinner_id in the
pool, no dinner twice and a note of at most 160 characters; one repair
turn, then ErrBadOutput. Repeating more of last week's dinners than the
pool made necessary is a warning, not a failure. is_new and a crock-pot
dinner's start-by time are computed in code. A pool of fewer than seven
dinners fails with NotEnoughDinnersError before any LLM call.

Maestro task 7ab59240-a4fd-43cf-b195-4698c8747491.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/ai/skills/testdata/draft_week_valid.system.golden

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+## Instructions
+You draft the household's dinner plan for one week, Monday to Sunday: one dinner for each day, chosen from the candidate pool in the household context.
+
+Rules:
+- Give exactly 7 days, one for each date of the week, in order from Monday to Sunday, each date written as YYYY-MM-DD.
+- Use only dinners from the candidate pool, each by its id exactly as the pool writes it.
+- Plan each dinner at most once in the week.
+- Avoid the dinners marked "planned last week" whenever the pool has enough others.
+- Mix the week: vary cuisines and methods, put quick dinners (a crockpot or 30 minutes or less) on weeknights, and include a Quest log dinner when the pool has one.
+
+Give:
+- days: the 7 days, each with date and dinner_id.
+- note: one sentence of at most 160 characters about the week.
+
+One valid day, for a pool with a dinner whose id is "d1" (an example only, not about this household):
+{"date": "2026-01-05", "dinner_id": "d1"}
+
+## Household context
+### Today
+- Thursday 2026-10-08 (America/New_York)
+
+### Regulars
+- Beef Chili (Tex-Mex, crockpot, 240 min)
+- Chicken Fajitas (Tex-Mex, stovetop, 30 min, favorite)
+
+### Quest log
+- Pad Thai
+
+### Passed, oldest first
+(none)
+
+### Recent plans
+- 2026-10-05 Mon: Chicken Fajitas
+- 2026-10-06 Tue: Fish Tacos
+
+### Candidate pool
+- id "chili": Beef Chili (Regular, crockpot, 240 min)
+- id "fajitas": Chicken Fajitas (Regular, stovetop, 30 min, planned last week)
+- id "bolognese": Spaghetti Bolognese (Regular, stovetop, 45 min)
+- id "salmon": Sheet Pan Salmon (Regular, oven)
+- id "tacos": Fish Tacos (Regular, 25 min, planned last week)
+- id "padthai": Pad Thai (Quest log, stovetop, 35 min)
+- id "roast": Pot Roast (Regular, crockpot)
+- id "shawarma": Chicken Shawarma Bowls (Quest log, oven, 40 min)
+
+## Output contract
+This contract overrides any earlier instruction about the form of your reply. Reply with one JSON value matching the JSON Schema "draft_week" below, and nothing else: no prose and no Markdown code fences.
+
+{
+  "type": "object",
+  "properties": {
+    "days": {
+      "type": "array",
+      "items": {
+        "type": "object",
+        "properties": {
+          "date": {
+            "type": "string"
+          },
+          "dinner_id": {
+            "type": "string"
+          }
+        },
+        "required": [
+          "date",
+          "dinner_id"
+        ],
+        "additionalProperties": false
+      }
+    },
+    "note": {
+      "type": "string"
+    }
+  },
+  "required": [
+    "days",
+    "note"
+  ],
+  "additionalProperties": false
+}

internal/ai/skills/testdata/draft_week_valid.user.golden

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+Draft the week of Mon 2026-10-12, Tue 2026-10-13, Wed 2026-10-14, Thu 2026-10-15, Fri 2026-10-16, Sat 2026-10-17, Sun 2026-10-18.