chat: clicking the title goes back to the conversation list

Same path as the back-caret — a bigger, easier target than the
icon. No-op when already on the list.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

public/plugins/chat/chat.html

@@ -3,7 +3,7 @@
 <div id="chat-flyout" class="hidden">
     <div id="chat-flyout-header">
         <i class="ph ph-chats-circle text-t-accent text-sm"></i>
-        <span id="chat-flyout-title" class="font-pixel text-[10px] text-t-bright">chat</span>
+        <span id="chat-flyout-title" class="font-pixel text-[10px] text-t-bright cursor-pointer hover:text-t-accent transition-colors" title="back to conversations">chat</span>
         <button id="chat-header-back" class="hidden text-t-muted hover:text-t-accent transition-colors" data-tip="back to list"><i class="ph ph-caret-left text-sm"></i></button>
         <span class="flex-1"></span>
         <button id="chat-thread-disposable" class="hidden text-t-muted hover:text-t-accent transition-colors" data-tip="disposable: messages drop after delivery"><i class="ph ph-fire text-sm"></i></button>