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/delete_device_file_alias.md

@@ -1,3 +1,11 @@
+---
+method: DELETE
+path: /api/devices/:id/file-aliases/:aliasId
+auth: jwt
+area: book-matching
+---
+<!-- source: internal/handlers/matching.go:287 MatchingHandler.DeleteDeviceFileAlias -->
+
 # Delete Device File Alias
 
 Delete a device file alias.
@@ -29,6 +37,12 @@ Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...
 
 File alias deleted successfully.
 
+```json example-response
+{
+  "message": "File alias deleted successfully"
+}
+```
+
 ## Error Responses
 
 | Code | Description                    |