Turn auth toggle into link

wwwroot/app.js

@@ -327,7 +327,10 @@ function renderPhaseTitles() {
 function setupHandlers() {
   const toggleAuth = $("auth-toggle");
   if (toggleAuth) {
-    toggleAuth.addEventListener("click", () => setAuthMode(state.authMode === "login" ? "register" : "login"));
+    toggleAuth.addEventListener("click", (e) => {
+      e.preventDefault();
+      setAuthMode(state.authMode === "login" ? "register" : "login");
+    });
   }
   setAuthMode(state.authMode);