Monolithic api-reference.md:
- New 'System Settings & Configuration' and 'Hash Conflicts' sections
(endpoints, examples, response shapes) with TOC entries
- Device Management: add the sidecar config/download endpoints
- Fix stale registration flow: correct auth_url path, drop phantom
device_id, add poll_interval/setup_instructions, status endpoint is
POST /api/devices/register/status, and sync_endpoints point at
/api/sync/koreader/*
- Mark PUT /api/libraries/scan-settings as legacy/superseded
- Repair Additional Resources and Collections links (dead
COLLECTIONS_API.md / KOBO*_SETUP.md / missing-guide references)
Split api-reference.md index:
- Quick links and sections for System (settings + config) and the
admin hash-conflict endpoints; device sidecar endpoints under Device
Management; browse + legacy scan-settings routes under Libraries