feat: use postgres

mail/internal/app/app.go

@@ -114,6 +114,11 @@ func classifyComponentResult(parentCtx context.Context, result componentResult)
 		return fmt.Errorf("run mail app: component %d exited without error before shutdown", result.index)
 	case errors.Is(result.err, context.Canceled) && parentCtx.Err() != nil:
 		return nil
+	case errors.Is(result.err, context.DeadlineExceeded) && parentCtx.Err() != nil:
+		// In-flight provider sends bound by their own short timeout race with
+		// the parent context cancel; either outcome is benign here because the
+		// claim will be recovered by the next runtime instance.
+		return nil
 	default:
 		return fmt.Errorf("run mail app: component %d: %w", result.index, result.err)
 	}