account list now routes to the agent role; an agent (EMCLI_KEY only) gets a
JSON envelope of name/from/can_send, while the admin keeps the full text
table. account add/edit/remove stay admin-only.
Also emit the agent path's missing-key/open failure as a JSON Failure
envelope (per spec), and update the stale run_test case that asserted the
old admin-only behavior.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
