Add the archive_title skill and title Supply runs on generation

archive_title v1 writes a Supply run's post title for the Supply archive
from the week's dinner names in day order. Validation requires 1-48
characters on one line, no emoji and no surrounding quotation marks; a
reply breaking a rule gets the harness's one repair turn.

shopping.Generate and GeneratePushed run it, outside the generation's
transaction, whenever the stored list is still untitled, and store
shopping_lists.title only while the list is untitled and not frozen. A
title failure never fails the generation: the list stays untitled, the
failure is logged and recorded in ai_runs, and the week's next
generation tries again. A titled list keeps its title on remakes.

Maestro task fa4b94c9-6623-41ab-8d2a-0ca7d1e6401a.

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

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

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+## Instructions
+You title the household's Supply run, the week's shopping list, as it is filed in the Supply archive: a blog-style history of the household's weeks of dinners. Write one short, warm, playful post title for the week, drawn from its dinners.
+
+Rules:
+- At most 48 characters, on one line.
+- Words only: no emoji.
+- No quotation marks around the title.
+- Do not name a date or week number; the archive shows those.
+
+Give:
+- title: the title.
+
+One valid reply, for a week of Beef Chili, Pot Roast and Fish Tacos (an example only, not about this household):
+{"title": "Slow Simmers and Taco Night"}
+
+## Household context
+No household context.
+
+## Output contract
+This contract overrides any earlier instruction about the form of your reply. Reply with one JSON value matching the JSON Schema "archive_title" below, and nothing else: no prose and no Markdown code fences.
+
+{
+  "type": "object",
+  "properties": {
+    "title": {
+      "type": "string"
+    }
+  },
+  "required": [
+    "title"
+  ],
+  "additionalProperties": false
+}

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

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+Title the week whose dinners are, in day order from Monday:
+- Beef Chili
+- Pot Roast
+- Chicken Fajitas
+- Spaghetti Bolognese
+- Sheet Pan Salmon
+- Pad Thai
+- Fish Tacos