修复频道筛选框被遮挡：header+filter 包裹在 sticky 容器中一起固定

meshmap_frontend/src/components/ChatPanel.vue

@@ -186,6 +186,7 @@ onUpdated(() => {
 
 <template>
   <aside ref="panelRef" class="chat-panel panel" @scroll.passive="handleScroll">
+    <div class="chat-panel-sticky">
       <div class="panel-header">
         <div>
           <p class="eyebrow">Chat</p>
@@ -209,6 +210,7 @@ onUpdated(() => {
           @click="emit('update:channelFilter', '')"
         >清除</button>
       </div>
+    </div>
 
     <div v-if="loadingOlder" class="chat-loading">正在加载更早消息...</div>
     <div v-else-if="!hasMoreMessages && messages.length > 0" class="chat-end">没有更多历史消息</div>

meshmap_frontend/src/style.css

@@ -299,7 +299,7 @@ h3 {
   overflow-y: auto;
 }
 
-.chat-panel .panel-header {
+.chat-panel-sticky {
   position: sticky;
   z-index: 10;
   top: 0;