drop the import the gate left behind

c59df4f removed the isSuperAdmin middleware and left its import, so the only two
matches in the file were the dead import and the comment explaining what used to
be there. Harmless and misleading: a grep for isSuperAdmin should not find chat.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/servers/api/chat/chat.ts

@@ -1,6 +1,5 @@
 import type { Context } from 'hono';
 import { createRouter } from '../../create-router';
-import { isSuperAdmin } from '@@/super-admin';
 import * as errors from '@@/custom-errors';
 import * as sidecar from '@@/sidecar-registry';
 import { getUserSettings } from 'officerdb';