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/progress/update_media_progress.md

@@ -1,3 +1,11 @@
+---
+method: PUT
+path: /api/media-items/:id/progress
+auth: jwt
+area: media-items
+---
+<!-- source: internal/handlers/media.go:1275 MediaHandler.UpdateMediaReadingProgress -->
+
 # Update Media Item Progress
 
 Submit reading progress for a media item. This is the position-authority
@@ -41,7 +49,7 @@ Authorization: Bearer eyJhbGciOiJIUzI1NiIs...
 Content-Type: application/json
 ```
 
-```json
+```json example-request
 {
   "percentage": 0.0415,
   "context_text": "was at war with one of these Powers it was generally at peace with the other. But what was strange w",
@@ -77,6 +85,36 @@ Content-Type: application/json
 
 ## Response (200 OK)
 
+```json example-response
+{
+  "id": "e8239659-0ed6-42ae-a946-8440d7655b42",
+  "media_item_id": "774641f9-317b-4087-8e04-53bb4392ae56",
+  "user_id": "1b64992e-3408-4d84-9e03-e2dc4950e1dd",
+  "current_page": null,
+  "total_pages": null,
+  "last_read_at": "2026-09-26T14:52:34.806446Z",
+  "percentage": 0.045,
+  "character_offset": 16375,
+  "epubcfi": "epubcfi(/6/4!/4/8[_idContainer003]/58/1:598)",
+  "context_text": null,
+  "chapter": null,
+  "chapter_progress": null,
+  "audio_offset_seconds": null,
+  "viewport_x": null,
+  "viewport_y": null,
+  "zoom_level": null,
+  "scroll_position_x": null,
+  "scroll_position_y": null,
+  "panel_number": null,
+  "reading_mode": "reflowable",
+  "last_sync_device": "web",
+  "last_sync_source": "koreader",
+  "last_sync_timestamp": "2026-09-26T14:52:34.806446Z",
+  "conflict_detected": false,
+  "conflict_resolved": false
+}
+```
+
 The saved progress row (same shape as
 [GET](get_media_progress.md), minus the GET-time handles). The
 `epubcfi` and `percentage` in the response are the server-verified