feat(renderer): StatusBar placeholder (word count wired in Phase 3)

src/renderer/components/layout/StatusBar.tsx

@@ -0,0 +1,14 @@
+export function StatusBar() {
+  return (
+    <footer className="flex h-7 items-center justify-between border-t border-border bg-card/20 px-3 text-xs text-muted-foreground">
+      <div className="flex items-center gap-4">
+        <span>0 words</span>
+        <span>UTF-8</span>
+      </div>
+      <div className="flex items-center gap-4">
+        <span>Ln 1, Col 1</span>
+        <span>Markdown</span>
+      </div>
+    </footer>
+  );
+}