Initial commit.

app/static/js/app.js

@@ -0,0 +1,18 @@
+(function themeInit() {
+  try {
+    const html = document.documentElement;
+    const select = document.getElementById("theme-select");
+    const saved = localStorage.getItem("theme") || "light";
+    html.setAttribute("data-theme", saved);
+    if (select) {
+      select.value = saved;
+      select.addEventListener("change", () => {
+        const value = select.value;
+        html.setAttribute("data-theme", value);
+        localStorage.setItem("theme", value);
+      });
+    }
+  } catch (e) {
+    // no-op
+  }
+})();