Editor: live settings sync + session-death banner

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

ui/src/app/editor-window/editor-window.html

@@ -89,6 +89,16 @@
       </div>
     }
 
+    @if (sessionDead()) {
+      <div
+        class="flex shrink-0 items-center gap-2 border-b border-border bg-destructive/10 px-3 py-1.5 text-[11px] text-destructive"
+      >
+        <ng-icon name="mynaXCircle" size="0.85rem" class="shrink-0" />
+        Disconnected from {{ ctx.sessionTitle }} — saving will fail, but your text is preserved
+        in this window.
+      </div>
+    }
+
     @if (loading()) {
       <div class="flex flex-1 items-center justify-center">
         <ng-icon name="mynaSpinner" size="1.25rem" class="animate-spin text-primary" />