优化前端，修改返回逻辑，添加视频实时背景，音量倍速持久化

app/components/BackButton.tsx

@@ -14,8 +14,8 @@ type BackButtonProps = {
 
 /**
  * BackButton
- * - Primary: behaves like browser back (router.back()), preserving previous page state (e.g., scroll, filters)
- * - Fallback: if no history entry exists (e.g., opened directly), navigates to '/'
+ * - Primary: attempts to close the current window/tab (window.close())
+ * - Fallback: if close fails (e.g., not opened by script), navigates to '/'
  * - Uses <Link> so that Ctrl/Cmd-click or middle-click opens the fallback URL in a new tab naturally
  */
 export default function BackButton({ className, ariaLabel = '返回', hrefFallback = '/', children }: BackButtonProps) {
@@ -25,13 +25,21 @@ export default function BackButton({ className, ariaLabel = '返回', hrefFallba
     // Respect modifier clicks (new tab/window) and non-left clicks
     if (e.button !== 0 || e.metaKey || e.ctrlKey || e.shiftKey || e.altKey) return;
 
-    // Prefer SPA back when we have some history to go back to
-    if (typeof window !== 'undefined' && window.history.length > 1) {
-      e.preventDefault();
-      router.back();
+    e.preventDefault();
+    
+    // Try to close the window first
+    if (typeof window !== 'undefined') {
+      window.close();
+      
+      // If window.close() didn't work (window still open after a short delay),
+      // navigate to the fallback URL
+      setTimeout(() => {
+        if (!document.hidden) {
+          router.push(hrefFallback);
+        }
+      }, 80);
     }
-    // else: allow default <Link href> to navigate to fallback
-  }, [router]);
+  }, [router, hrefFallback]);
 
   return (
     <Link