fix(cropper): make load failures visible; loud config errors

'Load next queued' did nothing because the running server had been started
without its env file (a restart used '-f .env' from tools/, where no .env
exists), so the cropper was unconfigured and every action answered 503 —
and none of that was visible, because notifications never rendered either:

- notifications used cds-toast/cds-toast-item, which the Carbon bundle does
  not define; a cds-toast-notification element renders nothing standalone in
  this build. The cropper now uses cds-inline-notification in the fixed
  toast viewport (renders, themed, close button) like the wizard
- an unconfigured deployment now says so on the page (503 'Cropper
  unavailable') instead of rendering actions that all fail, and logs a
  startup warning naming the missing credentials
- tests: notifications use a registered element; unconfigured page 503

tools/public/assets/cropper/index.html

@@ -37,10 +37,9 @@
 
     <!-- notifications -->
     <div class="toast-viewport" aria-live="polite">
-      <cds-toast>
-        <cds-toast-item v-for="t in toasts" v-bind:key="t.id" v-bind:kind="t.kind"
-                        v-bind:title="t.title" v-bind:caption="t.caption" timeout="6000"></cds-toast-item>
-      </cds-toast>
+      <cds-inline-notification v-for="t in toasts" v-bind:key="t.id" v-bind:kind="t.kind"
+                               v-bind:title="t.title" v-bind:subtitle="t.caption" low-contrast
+                               v-on:cds-notification-closed="removeToast(t.id)"></cds-inline-notification>
     </div>
 
     <!-- 1 · load -->