feat: app reports ready only after the startup migration run (E00-S03-T06)

packages/database-postgres/src/runner.ts

@@ -28,6 +28,9 @@
  * allowed to import the PostgreSQL driver (E00-S03-T02) — and talks to the
  * database exclusively through the package-owned `pg` Pool and the
  * `MigrationLedger`, so no other package needs the driver to run migrations.
+ * The app (apps/server) runs this runner at startup and gates its readiness
+ * on the run (E00-S03-T06): it does not report ready before the run
+ * completes.
  *
  * Rollback note from the issue: revert the diagnostic/error handling changes.
  */
@@ -128,7 +131,8 @@ function structuredCause(cause: unknown): Record<string, unknown> {
  * The migration runner: applies pending migrations in order, exactly once,
  * through the migration ledger. Instances are cheap and share the caller's
  * pool and ledger; the runner performs no locking (advisory lock is
- * E00-S03-T04) and no ready gating (E00-S03-T06).
+ * E00-S03-T04) and no ready gating (the app gates its readiness on the run,
+ * E00-S03-T06).
  */
 export class MigrationRunner {
   private readonly pool: Pool;