Show toggle button only when completed todos exist

Wrapped the toggle button in a conditional to display it only if there are completed todos in the current project filter. This prevents showing the toggle when there are no completed tasks to display.

Author: dongrentianyu

src/taskhub/ui/buttons/ToggleCompletedTodos.tid

@@ -1,7 +1,8 @@
 title: $:/plugins/mabuqian/TaskHub/ui/buttons/ToggleCompletedTodos
 
-\define lingo-base() $:/language/TaskHub/
+\procedure lingo-base() $:/language/TaskHub/
 
+<%if [subfilter{!!tmo_projectFilter}!tmo_taskState[todo]count[]!match[0]] %>
 <$vars stateTiddler=<<qualify "$:/state/TaskHub/show-completed">>
   default={{$:/config/TaskHub/ShowCompletedTodos}}>
 
@@ -25,4 +26,5 @@ title: $:/plugins/mabuqian/TaskHub/ui/buttons/ToggleCompletedTodos
       />
       </div>
     </$reveal>
-  </$vars>
+  </$vars>
+<%endif%>