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/app.js

@@ -54,10 +54,6 @@ Vue.config.ignoredElements = [/^cds-/];
     },
 
     computed: {
-      initials: function () {
-        var n = (this.session && (this.session.firstName || this.session.phone)) || '?';
-        return n.slice(0, 2).toUpperCase();
-      },
       canReview: function () {
         if (this.busy.review) return false;
         if (this.accepted) return true;