Schema-only change. DDL adds tier + topic on fresh tables and uses
ADD COLUMN IF NOT EXISTS on existing tables (idempotent across pod
restarts). New conditional indexes match the wing/hall pattern.
No behavior change in this commit — UpsertEntity still writes only
the original columns; tier + topic stay '' on every row. M2 plumbs
the parser through. The empty default means existing queries are
untouched until the rest of the chain lands.
Part of infra#72 — brain DIKW tier redesign.
ea9518e712