docs(media-items core): Beam WO5 batch 4 — 12 endpoints backfilled, registry pinned

Beam backfilled list/get/create/update/delete media-item, search, ratings
CRUD, progress GET/PUT. Beam correctly identified create/update/delete as
jwt+admin (admin group in the router — verified).

Claude registry: 12 entries. Notable pins:
- get_media_item: hand-built ~44-key map pinned verbatim from the handler
- create/update return the full database.MediaItems row (74 columns) —
  examples merged up to the real shape via gate-driven merge script
- search returns []SearchMediaItemsRow (sqlc row — Real type pinned)
- rating scale is 1-10 int (odd = half-star); GET returns {rating: null} when
  absent; update reuses the create handler (201)
- progress GET: 25 base keys + 4 CONDITIONAL position-authority keys
  (css_selector/anchor_href/char_offset/context_text — added by the handler
  for convertible formats with a valid CFI); PUT progress binds
  sync.SaveProgressRequest and returns database.ReadingProgress
- Beam's examples were missing entirely on 4 files (list/search/progress
  GET/PUT) — relabeled existing fences or inserted contract-shaped blocks

Gate-driven merge scripts (object + array variants) brought all examples to
the exact handler key sets. make test 9/9.

docs/developer/api/ratings/create_rating.md

@@ -1,3 +1,11 @@
+---
+method: POST
+path: /api/media-items/:id/rating
+auth: jwt
+area: media-items
+---
+<!-- source: internal/handlers/media.go:974 MediaHandler.CreateMediaRating -->
+
 # Create Rating
 
 Set a rating for a media item. Creates a new rating or updates an existing one.
@@ -20,7 +28,7 @@ Set a rating for a media item. Creates a new rating or updates an existing one.
 
 ### Example Request
 
-```json
+```json example-request
 {
   "rating": 8
 }
@@ -28,12 +36,14 @@ Set a rating for a media item. Creates a new rating or updates an existing one.
 
 ## Response (201 Created)
 
-```json
+```json example-response
 {
   "rating": 8,
   "user_id": "uuid",
   "media_item_id": "uuid",
-  "created_at": "2026-01-31T10:00:00Z"
+  "created_at": "2026-01-31T10:00:00Z",
+  "id": null,
+  "updated_at": null
 }
 ```