fix(blocks): replace 12px/14px font shorthands with var(--step-1)

check-tokens would only catch 'font-size: 14px' explicitly, but the
agent rule forbids slipping past it via the 'font:' shorthand. The
12px and 14px values had no matching token in --step-*; var(--step-1)
(15px) is the closest and preserves the column read. Token-layer gap
for 12px and 14px reported in the final report.

src/components/blocks/HandoffTable.astro

@@ -69,8 +69,11 @@ const { columns, rows } = Astro.props;
   }
   .handoff-table tbody th {
     color: var(--blue);
+    /* Source uses 14px; no token in --step-* matches. var(--step-1) is 15px,
+       close enough that the column reads the same. Token-layer gap reported
+       in the task final report. */
     font:
-      600 14px 'DM Mono',
+      600 var(--step-1) 'DM Mono',
       monospace;
   }
   .handoff-table td {