docs(api): update existing documentation

- Update api-reference.md with current endpoint list

- Update bulk_update_books.md with improved documentation

- Update scanner/overview.md to reference scan_library.md

docs/developer/api/scanner/overview.md

@@ -139,7 +139,7 @@ GET /api/scanner/status/550e8400-e29b-41d4-a716-446655440000
 
 ## Related Endpoints
 
-- [Scan Ebooks](scan_ebooks.md) - Manual one-time scan
+- [Scan Library](scan_library.md) - Manual one-time scan
 - [Start Scanner](start_scanner.md) - Automated periodic scanning
 - [Stop Scanner](stop_scanner.md) - Stop automated scanner
 - [Get Scan Status](get_scan_status.md) - Check scan progress