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_library.md

@@ -1,3 +1,11 @@
+---
+method: GET
+path: /api/sync/koreader/library
+auth: device-token
+area: koreader
+---
+<!-- source: internal/handlers/koreader.go:1391 KOReaderHandler.GetLibrary -->
+
 # Get Library
 
 Get library metadata for KOReader device.
@@ -26,18 +34,11 @@ X-Device-Key: device-auth-key
 
 ## Response (200 OK)
 
-```json
+```json example-response
 {
-  "books": [
-    {
-      "id": "uuid",
-      "title": "Book Title",
-      "authors": ["Author Name"],
-      "file": "book.epub",
-      "size": 1234567
-    }
-  ],
-  "total": 42
+  "last_sync": null,
+  "library_sync": null,
+  "total_books": null
 }
 ```