Revert unintentional mouse movement changes

Reverts the mouse handler changes that were accidentally included in the previous commit. Restores the timer-based mouseMoveHandler function and @mouseover event handler.

Co-Authored-By: Claude Sonnet 4.5 <[e-mail]>

src/App.vue

···
 const showSettingsButton = ref(false)
 let showSettingsTimer: number | undefined = undefined
 
-function mouseMoveHandler(set: boolean) {
-  showSettingsButton.value = set
+function mouseMoveHandler() {
+  clearTimeout(showSettingsTimer)
+  showSettingsButton.value = true
+  showSettingsTimer = setTimeout(() => {
+    showSettingsButton.value = false
+  }, 5000)
 }
 
 startChat()
 </script>
 
 <template>
-  <div @mouseenter="mouseMoveHandler(true)" @mouseleave="mouseMoveHandler(false)" id="chatContainer">
+  <div @mouseover="mouseMoveHandler" id="chatContainer">
     <div id="chats">
       <p class="chatLine" v-for="chat in chatMessages">
         <span class="chatHandle"