ORDER BY created_at DESC, id DESC but cursor was `WHERE created_at <
$2` — when two users were created at the same instant, pagination
could skip the second row at a page boundary or return it twice.
- Add ListCursor { created_at, id } with `<rfc3339>_<uuid>` encode /
decode helpers.
- Change WHERE predicate to `(created_at, id) < ($2, $3)` matching the
ORDER BY.
- Surface the opaque cursor string through UsersListOpts /
UsersListPage / users_admin_api ListUsersResponse instead of the raw
DateTime — keeps the wire format stable while the id half stops the
boundary bug.
Same shape as F-P-005 (execution_logs).
AUDIT.md anchor: F-P-012.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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