29-Apr-2026 — satisfy pre-push lint:all on existing server files

build 629 — commit 47903f2

Pre-push lint:all flagged two errors that pre-commit (staged-files only) had let through:

• aws-controllers.ts:259 used a typeof check for the download query string; switched to !isString() from es-toolkit/compat per the no-restricted-syntax rule.

• 20260424000000-backfill-walk-leader-from-member.ts:62 iterated the cursor with an imperative while loop; switched to 'for await (const walk of cursor)' matching the pattern in 20260427100000-purge-orphan-mail-list-audit.ts.