feat(ui): ui-shell header with tool links, mobile side nav, Youreka logo

- header: Carbon ui-shell (cds-header) with the Youreka logo (from
  idid-enterprise-portal), Image Cropper / Fingerprint Agent nav items
  (aria-current on the active tool), the agent status tag on the wizard,
  and the operator chip + Sign out on desktop
- mobile: cds-side-nav (logo above the items, both tools, a divider, then
  Sign out) toggled by the ui-shell menu button; account actions move out
  of the header below 1056px, the nav is hidden at desktop widths
- the header is built once in server.js (appHeader) and injected into the
  landing, both tools and error pages — no per-page duplication
- removed my duplicate menu-button toggle: ui-shell coordinates the menu
  button and side nav itself (the duplicate cancelled it out)
- fixes: 'cds-header' was hidden by a selector-list typo
  (cds-header, cds-side-nav:not(:defined)); the collapsed side nav no
  longer captures taps

Tools banner logo asset added (public/assets/youreka-logo.png).

tools/public/assets/cropper/index.html

@@ -12,6 +12,7 @@
   <script src="https://cdn.jsdelivr.net/npm/vue-croppa@1.3.8/dist/vue-croppa.min.js"></script>
   <script src="https://unpkg.com/axios/dist/axios.min.js"></script>
   <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/vue-croppa@1.3.8/dist/vue-croppa.min.css">
+  <script type="module" src="https://1.www.s81c.com/common/carbon/web-components/version/v2.50.0/ui-shell.min.js"></script>
   <script type="module" src="https://1.www.s81c.com/common/carbon/web-components/version/v2.50.0/button.min.js"></script>
   <script type="module" src="https://1.www.s81c.com/common/carbon/web-components/version/v2.50.0/notification.min.js"></script>
   <script type="module" src="https://1.www.s81c.com/common/carbon/web-components/version/v2.50.0/tag.min.js"></script>
@@ -23,23 +24,7 @@
 </head>
 <body class="app">
 <div id="app">
-  <nav class="nav">
-    <div class="container">
-      <a class="brand" href="/">
-        <span class="brand-mark">
-          <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true"><path d="M6 2v14a2 2 0 0 0 2 2h14"/><path d="M18 22V8a2 2 0 0 0-2-2H2"/></svg>
-        </span>
-        YOUreka <small>Tools</small>
-      </a>
-      <div class="nav-right" v-cloak v-if="session">
-        <span class="user-chip">
-          <span class="avatar">{{ initials }}</span>
-          {{ session.firstName || session.phone }}
-        </span>
-        <a class="linklike" href="/auth/logout">Sign out</a>
-      </div>
-    </div>
-  </nav>
+  <!--app-header-->
 
   <main class="container" v-cloak v-if="session">
     <div class="page-head">