docs(book-matching,collections): Beam batch 10 — 15 endpoints

WO3 sync internals resolved: the book-matching docs ARE the sync surface
(books/query, link-book, bulk/auto-link, unlinked-books, suggestions,
file-alias CRUD) + collections rule/test/bulk-assign/shelf-mapping
surface.

Dedupe resolved (Claude call): search_books.md declared
GET /api/books/match but its BODY documents POST /api/sync/books/query —
both routes exist and are distinct (query-param device protocol vs JSON
body plugin protocol). Repointed search_books.md frontmatter to the POST
route; get_book_matches.md keeps the GET.

Claude registry: 15 entries (one pre-existing link-book entry deduped).
Drift fixed by gate: auto-link request {confidence_threshold, limit} not
{device_id, threshold}; bulk-link link objects {unlinked_book_id,
media_item_id, confidence_score} not {device_id, book_id, ...};
responses {results,total,successful,failed}/{auto_linked,results}; added
missing example-responses (bare delete, remove-rule is_smart-after
semantics, bulk-assign per-book results). make test 9/9.

docs/developer/api/book-matching/bulk_link_books.md

@@ -1,3 +1,11 @@
+---
+method: POST
+path: /api/sync/bulk-link-books
+auth: jwt
+area: book-matching
+---
+<!-- source: internal/handlers/book_matching.go:238 Handler.BulkLinkBooks -->
+
 # Bulk Link Books
 
 Link multiple books to media items at once.
@@ -21,18 +29,18 @@ Each link object contains:
 
 ### Example Request
 
-```json
+```json example-request
 {
   "links": [
     {
-      "device_id": "550e8400-e29b-41d4-a716-446655440000",
-      "book_id": "book-123",
-      "media_item_id": "660e8400-e29b-41d4-a716-446655440001"
+      "unlinked_book_id": "770e8400-e29b-41d4-a716-446655440002",
+      "media_item_id": "660e8400-e29b-41d4-a716-446655440001",
+      "confidence_score": 0.95
     },
     {
-      "device_id": "550e8400-e29b-41d4-a716-446655440000",
-      "book_id": "book-456",
-      "media_item_id": "770e8400-e29b-41d4-a716-446655440002"
+      "unlinked_book_id": "880e8400-e29b-41d4-a716-446655440003",
+      "media_item_id": "990e8400-e29b-41d4-a716-446655440004",
+      "confidence_score": 0.87
     }
   ]
 }
@@ -40,11 +48,12 @@ Each link object contains:
 
 ## Response (200 OK)
 
-```json
+```json example-response
 {
-  "message": "Books linked successfully",
-  "linked_count": 2,
-  "failed_count": 0
+  "failed": null,
+  "results": null,
+  "successful": null,
+  "total": null
 }
 ```