The catch-up migration assumed sign_sessions already existed, but
databases created from older schema dumps may not have this table.
Adding CREATE TABLE IF NOT EXISTS prevents the migration from failing
with "relation does not exist" on those databases.
The migration consolidation (27fb0fa) merged 33 incremental patches
into 0001_init.sql and marks the baseline as applied for any existing
database. Users who only ran some of the 33 patches have schema gaps
that cause runtime errors.
0002_catch_up_patches.sql replays all 33 patches (skipping 15 and 20,
which are destructive data resets) with idempotency guards so it is a
no-op on fresh or fully-patched databases and fills gaps otherwise.
