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/initialization.md

@@ -1,3 +1,11 @@
+---
+method: GET
+path: /api/sync/kobo/:token/v1/initialization
+auth: device-token
+area: kobo
+---
+<!-- source: internal/handlers/kobo.go:282 KoboHandler.Initialization -->
+
 # Kobo Initialization
 
 > **Status: Coming Soon** — Native Kobo sync is not yet supported on real devices; this endpoint is under active development and may change.
@@ -29,13 +37,11 @@ X-Device-Key: device-auth-key
 
 ## Response (200 OK)
 
-```json
+```json example-response
 {
-  "result": "ok",
-  "resources": {
-    "image_host": "https://cdn.kobo.com/...",
-    "image_url_quality_template": "{ImageId}/h270/{ImageId}_landscape_cover.jpg"
-  }
+  "last_sync": null,
+  "library_sync": null,
+  "total_books": null
 }
 ```