feat(web): Pressing Plant component library + describeJob

design.css component classes (masthead, contents nav, tiles, dept header,
job row + severity stripe, status chip, progress bar, pressed list, buttons,
fields). Presentational _ui components. describeJob maps worker Job.state to
literal labels + severity kind + stepped progress (unit-tested).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web/src/app/_ui/stat-tiles.tsx

@@ -0,0 +1,17 @@
+export type Tile = { k: string; v: number | string; unit?: string; accent?: boolean };
+
+export function StatTiles({ items }: { items: Tile[] }) {
+  return (
+    <section className="tiles">
+      {items.map((t) => (
+        <div key={t.k} className={`tile${t.accent ? " accent" : ""}`}>
+          <div className="k">{t.k}</div>
+          <div className="v">
+            {t.v}
+            {t.unit ? <small>{t.unit}</small> : null}
+          </div>
+        </div>
+      ))}
+    </section>
+  );
+}