Build music-quiz installer and management site per spec

Implements the full spec described in README.md:

Management site (Node + TypeScript + Express + EJS):
- Public main page lists packs registered in manifest.json.
- /op login (account.json, internal-only), /op/dashboard manages packs
  with horizontal-scroll cards, add/select-and-delete flow, and the
  /op/dashboard/:packName editor (Mojang release dropdown, dynamic
  mods/resourcepacks lists, platform/RAM fields, file rename).
- Routes for /manifest.json (public) and /file/* (server pack files).
- Middleware blocks /account.json and /manifest/* directory access.

Installer (Electron):
- Five page renderer driven by IPC (preload contextBridge API):
  pack pick → single/multi → server install (path no-Korean check, JDK
  detect, file download, EULA, RAM gating, local web config editor,
  UPnP/port-forward check) → client install (.mc_custom mods +
  resourcepacks + launcher_profiles.json gameDir/javaArgs) → finish
  toggles (server folder, shortcut, server start, launcher start).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

views/partials/navbar.ejs

@@ -0,0 +1,30 @@
+<header class="topNav">
+  <a class="navBrand" href="/op/dashboard">
+    <span class="navLogo">🎵</span>
+    <span class="navTitle">관리자 페이지</span>
+  </a>
+  <div class="navUser">
+    <button type="button" class="navUserButton" id="userMenuToggle"><%= userId %></button>
+    <div class="navUserMenu" id="userMenu" hidden>
+      <form method="post" action="/op/logout">
+        <button type="submit" class="dangerLink">로그아웃</button>
+      </form>
+    </div>
+  </div>
+</header>
+<script>
+  (function () {
+    var toggle = document.getElementById('userMenuToggle')
+    var menu = document.getElementById('userMenu')
+    if (!toggle || !menu) return
+    toggle.addEventListener('click', function () {
+      var hidden = menu.hasAttribute('hidden')
+      if (hidden) menu.removeAttribute('hidden')
+      else menu.setAttribute('hidden', '')
+    })
+    document.addEventListener('click', function (event) {
+      if (event.target === toggle || menu.contains(event.target)) return
+      menu.setAttribute('hidden', '')
+    })
+  })()
+</script>