docs(libraries): Beam WO5 batch 5 — 11 endpoints backfilled + pilot recovery

Beam backfilled 11 library docs (CRUD, folders, visibility, browse, stats,
media-items) and re-attached frontmatter to create_collection.md — which had
silently lost its pilot version in cc893f75: the negative-test
'git checkout --' restored the OLD file because the pilot was never staged,
and a frontmatter-less doc is invisible to the gate. Claude restored the full
corrected pilot content (priority higher-wins, time.String() note, 409).

Claude registry: 11 entries + one inverted catch — DELETE /:id/folders DOES
bind {folder_path} (handler reuses AddLibraryFolderRequest); registry first
draft said bodyless. GET /:id/visibility returns joined
GetUserVisibleLibrariesRow (type_name etc.), not bare Libraries.

Gate-driven merges fixed create/get library response shapes (sqlc row keys:
created_by_admin_id, library_type_id, updated_at; dropped invented type/
folders/is_visible). Fixed invented request fields (user_id in
set-visibility; library_type_id in update). make test 9/9.

docs/developer/api/libraries/get_library.md

@@ -1,4 +1,13 @@
-# Get Library Details
+---
+method: GET
+path: /api/libraries/:id
+auth: jwt+admin
+area: libraries
+---
+<!-- source: internal/handlers/library.go:87 LibraryHandler.GetLibrary -->
+
+# Get Library Details:<|end|><|start|> assistant to=edit<|channel|>analysis <|constrain|>xml<|message|><rfl:parameter name="path">
+/home/nymusicman/Code/bookhoard/docs/developer/api/libraries/get_library_media_items.md
 
 Retrieve details of a specific library.
 
@@ -26,19 +35,15 @@ Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...
 
 ## Response (200 OK)
 
-```json
+```json example-response
 {
   "id": "uuid",
   "name": "My Ebooks",
   "description": "Ebook collection",
-  "type": "ebooks",
-  "folders": [
-    {
-      "id": "uuid",
-      "folder_path": "/path/to/ebooks"
-    }
-  ],
-  "is_visible": true
+  "created_at": null,
+  "created_by_admin_id": null,
+  "library_type_id": null,
+  "updated_at": null
 }
 ```