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

src/config/schema.rs

@@ -202,25 +202,37 @@ impl Default for HidConfig {
 pub struct MsdConfig {
     /// Enable MSD functionality
     pub enabled: bool,
-    /// Storage path for ISO/IMG images
-    pub images_path: String,
-    /// Path for Ventoy bootable drive file
-    pub drive_path: String,
-    /// Ventoy drive size in MB (minimum 1024 MB / 1 GB)
-    pub virtual_drive_size_mb: u32,
+    /// MSD base directory (absolute path)
+    pub msd_dir: String,
 }
 
 impl Default for MsdConfig {
     fn default() -> Self {
         Self {
             enabled: true,
-            images_path: "./data/msd/images".to_string(),
-            drive_path: "./data/msd/ventoy.img".to_string(),
-            virtual_drive_size_mb: 16 * 1024, // 16GB default
+            msd_dir: String::new(),
         }
     }
 }
 
+impl MsdConfig {
+    pub fn msd_dir_path(&self) -> std::path::PathBuf {
+        std::path::PathBuf::from(&self.msd_dir)
+    }
+
+    pub fn images_dir(&self) -> std::path::PathBuf {
+        self.msd_dir_path().join("images")
+    }
+
+    pub fn ventoy_dir(&self) -> std::path::PathBuf {
+        self.msd_dir_path().join("ventoy")
+    }
+
+    pub fn drive_path(&self) -> std::path::PathBuf {
+        self.ventoy_dir().join("ventoy.img")
+    }
+}
+
 // Re-export ATX types from atx module for configuration
 pub use crate::atx::{ActiveLevel, AtxDriverType, AtxKeyConfig, AtxLedConfig};