feat(frontend): add polling job queue ui

frontend/src/hooks/useTheme.ts

@@ -0,0 +1,23 @@
+import { useEffect, useState } from "react";
+
+type Theme = "light" | "dark";
+
+function initialTheme(): Theme {
+  const stored = window.localStorage.getItem("jobQueueTheme");
+  if (stored === "light" || stored === "dark") return stored;
+  return window.matchMedia("(prefers-color-scheme: dark)").matches ? "dark" : "light";
+}
+
+export function useTheme() {
+  const [theme, setTheme] = useState<Theme>(initialTheme);
+
+  useEffect(() => {
+    document.documentElement.dataset.theme = theme;
+    window.localStorage.setItem("jobQueueTheme", theme);
+  }, [theme]);
+
+  return {
+    theme,
+    toggleTheme: () => setTheme((current) => (current === "dark" ? "light" : "dark"))
+  };
+}