feat: 支持 MJPEG 解码与 MSD 目录配置

- FFmpeg/hwcodec 增加 RKMPP MJPEG 解码与 RAM FFI，ARM 构建启用对应解码器
  - 共享视频管线新增 MJPEG 解码路径（RKMPP/TurboJPEG），优化 WebRTC 发送与 MJPEG 去重
  - MSD 配置改为 msd_dir 并自动创建子目录，接口与前端设置同步更新
  - 更新包依赖与版本号

web/src/components/ActionBar.vue

@@ -49,8 +49,10 @@ const systemStore = useSystemStore()
 const overflowMenuOpen = ref(false)
 
 // MSD is only available when HID backend is not CH9329 (CH9329 is serial-only, no USB gadget)
+const hidBackend = computed(() => (systemStore.hid?.backend ?? '').toLowerCase())
+const isCh9329Backend = computed(() => hidBackend.value.includes('ch9329'))
 const showMsd = computed(() => {
-  return props.isAdmin && systemStore.hid?.backend !== 'ch9329'
+  return props.isAdmin && !isCh9329Backend.value
 })
 
 const props = defineProps<{
@@ -310,5 +312,5 @@ const extensionOpen = ref(false)
   </div>
 
   <!-- MSD Dialog -->
-  <MsdDialog v-model:open="msdDialogOpen" />
+  <MsdDialog v-if="showMsd" v-model:open="msdDialogOpen" />
 </template>

web/src/components/VideoConfigPopover.vue

@@ -114,6 +114,7 @@ function detectBrowserCodecSupport() {
 
 // Check if a codec is supported by browser
 const isBrowserSupported = (codecId: string): boolean => {
+  if (codecId === 'mjpeg') return true
   return browserSupportedCodecs.value.has(codecId)
 }
 
@@ -704,7 +705,7 @@ watch(currentConfig, () => {
                   v-for="format in availableFormats"
                   :key="format.format"
                   :value="format.format"
-                  :class="['text-xs', { 'opacity-50': isFormatNotRecommended(format.format) }]"
+                  class="text-xs"
                 >
                   <div class="flex items-center gap-2">
                     <span>{{ format.description }}</span>