The archive endpoints (list/get/delete/file/settings) are served by the front
(codai/frontproxy/admin_data.py, from disk via archive_manager), so the engine's
copies in admin/routes.py were dead. Removed.

Note: the cache/download/HF handlers in routes.py are NOT removed — the
coderai-system worker serves them through the same admin_router, so they're only
unrouted on the engine, not dead code. Fully removing them from the engine would
require splitting routes.py into engine vs system routers (future cleanup).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011DDv7BchtZQWsnPG6Jm49m