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/get_media_progress.md

@@ -1,3 +1,11 @@
+---
+method: GET
+path: /api/media-items/:id/progress
+auth: jwt
+area: media-items
+---
+<!-- source: internal/handlers/media.go:1173 MediaHandler.GetMediaReadingProgress -->
+
 # Get Media Item Progress
 
 Get the stored reading progress for a media item, plus the
@@ -37,7 +45,7 @@ returned (not 404):
 
 ## Response (200 OK) — progress stored
 
-```json
+```json example-response
 {
   "id": "e8239659-0ed6-42ae-a946-8440d7655b42",
   "media_item_id": "774641f9-317b-4087-8e04-53bb4392ae56",
@@ -59,7 +67,15 @@ returned (not 404):
   "css_selector": "body>div:nth-child(4)>p:nth-child(29)",
   "anchor_href": "1984.xhtml",
   "char_offset": 598,
-  "context_text": "from day to day, but there was none in which Goldstein was not the principal figure. He was the prim"
+  "context_text": "from day to day, but there was none in which Goldstein was not the principal figure. He was the prim",
+  "audio_offset_seconds": null,
+  "panel_number": null,
+  "reading_mode": null,
+  "scroll_position_x": null,
+  "scroll_position_y": null,
+  "viewport_x": null,
+  "viewport_y": null,
+  "zoom_level": null
 }
 ```