Phase 6: sync jobs, inquiry and order forms

- Sync scheduler in the content service with a per-job cache (sync_cache),
  sync_runs reporting and Healthchecks pings. Jobs: Archidekt, BoardGameGeek,
  cover art (Open Library, TMDB, AniList), Suwayomi and Kavita reading
  progress, Bambuddy filament and Homebox material stock. A note's own value
  always wins over a synced one.
- PersonalReader: updates only Library notes with a matching anilistId,
  changes to Greg's notes are held for review; Reading series with no note
  show as suggestions on the admin Overview.
- /api/inquiries and /api/orders: Turnstile, rate limits, a saved copy in the
  content service (intake token) plus email over SMTP. Orders are re-checked
  against the live notes: accepted only when the category's ordersOpen is
  true and the line has capacity.
- Admin Inbox for saved submissions. Options' inStock is optional so synced
  stock can fill it. All settings from process.env; .env.example per service.
- Sources could not be reached from the build environment; parsers are tested
  against fixtures labelled as not live.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012aSbo2D1qP8cMFQCykf7kx

services/content/test/sync/fixtures/anilist-page.sample.json

@@ -0,0 +1,15 @@
+{
+  "data": {
+    "Page": {
+      "media": [
+        { "id": 100001, "title": { "english": "Sample Tower Climber", "romaji": "Sample Tou" }, "format": "MANGA", "countryOfOrigin": "KR",
+          "coverImage": { "extraLarge": "https://s4.anilist.co/file/anilistcdn/media/manga/cover/large/sample-100001.jpg", "large": null } },
+        { "id": 100003, "title": { "english": null, "romaji": "Sample Owari" }, "format": "MANGA", "countryOfOrigin": "JP",
+          "coverImage": { "extraLarge": null, "large": "https://s4.anilist.co/file/anilistcdn/media/manga/cover/medium/sample-100003.jpg" } },
+        { "id": 100004, "title": { "english": "New Sample Series", "romaji": "Shin Sample" }, "format": "MANGA", "countryOfOrigin": "KR",
+          "coverImage": { "extraLarge": "https://s4.anilist.co/file/anilistcdn/media/manga/cover/large/sample-100004.jpg" } },
+        { "id": 100005, "title": { "english": "Sample Dropped" }, "format": "MANGA", "countryOfOrigin": "JP", "coverImage": {} }
+      ]
+    }
+  }
+}