fix(Live2D): Firefox kiosk 进程清理用 pkill 兜底

Firefox esr 会 fork 子进程，child.kill() 只杀父进程导致残留。
三处清理（ConfigReloaded live2d 分支/切回视频分支/stop）都加
pkill -f live2d-display.html 兜底。

src/plugins/video/mod.rs

@@ -214,6 +214,10 @@ impl Plugin for VideoPlugin {
                         let _ = child.kill();
                         let _ = child.wait();
                     }
+                    let _ = std::process::Command::new("pkill")
+                        .arg("-f")
+                        .arg("live2d-display.html")
+                        .output();
                     // 启动 Firefox kiosk 模式全屏显示 Live2D
                     let port = config.remote_control.port;
                     let url = format!("http://localhost:{port}/live2d-display.html");
@@ -242,8 +246,13 @@ impl Plugin for VideoPlugin {
                 if let Some(mut child) = self.live2d_child.take() {
                     let _ = child.kill();
                     let _ = child.wait();
-                    println!("[VideoPlugin] 切回视频模式：Firefox kiosk 已关闭");
                 }
+                // Firefox 会 fork 子进程，child.kill() 只杀父进程，用 pkill 兜底
+                let _ = std::process::Command::new("pkill")
+                    .arg("-f")
+                    .arg("live2d-display.html")
+                    .output();
+                println!("[VideoPlugin] 切回视频模式：Firefox kiosk 已关闭");
 
                 let processor = Arc::new(Mutex::new(VideoProcessor::new(config)?));
                 if let Some(old) = self.processor.replace(Arc::clone(&processor)) {
@@ -295,6 +304,10 @@ impl Plugin for VideoPlugin {
             let _ = child.kill();
             let _ = child.wait();
         }
+        let _ = std::process::Command::new("pkill")
+            .arg("-f")
+            .arg("live2d-display.html")
+            .output();
 
         self.publish_status();
         Ok(())