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/tmdb-search.sample.json

@@ -0,0 +1,9 @@
+{
+  "_sample": "Hand-written from TMDB's search/movie response shape; not a live response.",
+  "page": 1,
+  "results": [
+    { "id": 1, "title": "Arrival (short)", "poster_path": null },
+    { "id": 329865, "title": "Arrival", "release_date": "2016-11-10", "poster_path": "/x2FJsf1ElAgr63Y3PNPtJrcmpoe.jpg" }
+  ],
+  "total_results": 2
+}