docs(kobo,koreader,collections): Beam WO5 batch 6 — 12 endpoints

Kobo emulation + KOReader calibre-compatible surface backfilled with
device-token auth; collections reorder + update_rule created.

Claude registry: 12 entries. kobo/koreader emulation endpoints all bind
arbitrary protocol POST bodies (markup/bookmark/gettests/sync-from-server,
koreader progress/bookmarks) — registered as AnyJSONObject, not bodyless as
first drafted. Initialization returns the library sync payload, not the init
response.

Contract correction in update_rule.md: the route is SetRuleEnabled ({enabled}
required -> {collection_id, is_smart}); Beam's draft invented rule-field
updates. Reordered response/status: {item_ids} -> {status: reordered}.

make test 9/9.

docs/developer/api/koreader/get_metadata.md

@@ -1,3 +1,11 @@
+---
+method: GET
+path: /api/sync/koreader/metadata/:uuid
+auth: device-token
+area: koreader
+---
+<!-- source: internal/handlers/koreader.go:1025 KOReaderHandler.GetMetadata -->
+
 # Get Metadata
 
 Get a book's stored progress and annotations for a KOReader device —
@@ -23,7 +31,7 @@ Authorization: Bearer {device_token}
 
 ## Response (200 OK)
 
-```json
+```json example-response
 {
   "uuid": "774641f9-317b-4087-8e04-53bb4392ae56",
   "title": "1984",