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/kobo/bookmark_sync.md

@@ -1,3 +1,11 @@
+---
+method: POST
+path: /api/sync/kobo/:token/bookmark
+auth: device-token
+area: kobo
+---
+<!-- source: internal/handlers/kobo.go:613 KoboHandler.Bookmark -->
+
 # Bookmark Sync
 
 > **Status: Coming Soon** — Native Kobo sync is not yet supported on real devices; this endpoint is under active development and may change.
@@ -29,7 +37,7 @@ This endpoint requires device authentication (not user JWT). Kobo devices authen
 
 ### Example Request
 
-```json
+```json example-request
 {
   "bookmarks": [
     {
@@ -45,10 +53,11 @@ This endpoint requires device authentication (not user JWT). Kobo devices authen
 
 ## Response (200 OK)
 
-```json
+```json example-response
 {
-  "message": "Bookmarks synced successfully",
-  "synced_count": 1
+  "BookmarksSynced": null,
+  "MarkupsSynced": null,
+  "Status": null
 }
 ```