fix(admin): keep ticket internal notes compact

Show only the latest three notes and fold older ones into a details
toggle, collapse the note composer to one line until focused, and cap
the sidebar height to the dialog body so its controls stay reachable.

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

assets/js/admin-tickets.js

@@ -202,6 +202,8 @@
       updateUrl(id, data.page);
       setupForms(panel, restore);
       showLatest(false);
+      var notes = panel.querySelector('.aksrt-ticket-detail__notes');
+      if (notes) notes.scrollTop = notes.scrollHeight;
       stale = false;
       savedDrafts = {};
       savedMessage = '';
@@ -405,6 +407,12 @@
 
   // scroll 不冒泡，用捕获监听会话容器。
   panel.addEventListener('scroll', syncLatest, true);
+  // 把正文可视高度写给 CSS，用于限制右侧栏高度。
+  if (typeof ResizeObserver === 'function') {
+    new ResizeObserver(function () {
+      panel.style.setProperty('--aksrt-ticket-panel-height', panel.clientHeight + 'px');
+    }).observe(panel);
+  }
 
   window.addEventListener('beforeunload', function (event) {
     if (!saving && !dirty()) return;