feat(webrtc): 添加公共ICE服务器支持和优化HID延迟

- 重构ICE配置：将TURN配置改为统一的ICE配置，支持STUN和多TURN URL
- 添加公共ICE服务器：类似RustDesk，用户留空时使用编译时配置的公共服务器
- 优化DataChannel HID消息：使用tokio::spawn立即处理，避免依赖webrtc-rs轮询
- 添加WebRTCReady事件：客户端等待此事件后再建立连接
- 初始化时启动音频流，确保WebRTC可订阅
- 移除多余的trace/debug日志减少开销
- 更新前端配置界面支持公共ICE服务器显示

web/src/components/ActionBar.vue

@@ -1,7 +1,8 @@
 <script setup lang="ts">
-import { ref } from 'vue'
+import { ref, computed } from 'vue'
 import { useI18n } from 'vue-i18n'
 import { useRouter } from 'vue-router'
+import { useSystemStore } from '@/stores/system'
 import { Button } from '@/components/ui/button'
 import {
   Popover,
@@ -42,10 +43,16 @@ import MsdDialog from '@/components/MsdDialog.vue'
 
 const { t } = useI18n()
 const router = useRouter()
+const systemStore = useSystemStore()
 
 // Overflow menu state
 const overflowMenuOpen = ref(false)
 
+// MSD is only available when HID backend is not CH9329 (CH9329 is serial-only, no USB gadget)
+const showMsd = computed(() => {
+  return props.isAdmin && systemStore.hid?.backend !== 'ch9329'
+})
+
 const props = defineProps<{
   mouseMode?: 'absolute' | 'relative'
   videoMode?: VideoMode
@@ -100,7 +107,8 @@ const extensionOpen = ref(false)
         />
 
         <!-- Virtual Media (MSD) - Hidden on small screens, shown in overflow -->
-        <TooltipProvider v-if="props.isAdmin" class="hidden sm:block">
+        <!-- Also hidden when HID backend is CH9329 (no USB gadget support) -->
+        <TooltipProvider v-if="showMsd" class="hidden sm:block">
           <Tooltip>
             <TooltipTrigger as-child>
               <Button variant="ghost" size="sm" class="h-8 gap-1.5 text-xs" @click="msdDialogOpen = true">
@@ -253,8 +261,8 @@ const extensionOpen = ref(false)
             </Button>
           </DropdownMenuTrigger>
           <DropdownMenuContent align="end" class="w-48">
-            <!-- MSD - Mobile only -->
-            <DropdownMenuItem v-if="props.isAdmin" class="sm:hidden" @click="msdDialogOpen = true; overflowMenuOpen = false">
+            <!-- MSD - Mobile only, hidden when CH9329 backend -->
+            <DropdownMenuItem v-if="showMsd" class="sm:hidden" @click="msdDialogOpen = true; overflowMenuOpen = false">
               <HardDrive class="h-4 w-4 mr-2" />
               {{ t('actionbar.virtualMedia') }}
             </DropdownMenuItem>