feat(web): use history routing and preserve scroll on filter changes

reaction_board/web/static/app.js

@@ -43,7 +43,7 @@ function icon(name) {
 function renderNav() {
   const nav = document.querySelector("#bottom-nav");
   nav.innerHTML = NAV_ITEMS.map((item) => `
-    <a class="nav-item" href="#${item.path}" data-nav="${item.path}">
+    <a class="nav-item" href="${item.path}" data-nav="${item.path}">
       ${icon(item.icon)}<span class="nav-label">${item.label}</span>
     </a>`).join("");
 }