fix: 修复 VideoDecoder flush timeout 解码器超时卡死

- decoder.decode(chunk) 改为 await，捕获异步 rejection
- 添加 decodeErrors 计数，连续 3 次解码失败跳过当前片段
- flush 之前检查 decoder.state，只在 configured 状态才执行
- 避免在 error/closed 状态调用 flush 导致卡死

apps/web/src/pages/generate/hooks/useCanvasPlayer.ts

@@ -576,6 +576,7 @@ export function useCanvasPlayer(
       // 送入解码器
       let decodedCount = 0
       let skippedCount = 0
+      let decodeErrors = 0
       for (const sample of samplesCollected) {
         if (!sample.data || isDestroyedRef.current) {
           skippedCount++
@@ -591,27 +592,30 @@ export function useCanvasPlayer(
         })
 
         try {
-          decoder.decode(chunk)
+          await decoder.decode(chunk) // 修复：await 捕获异步错误
           decodedCount++
         } catch (e) {
-          console.warn("[useCanvasPlayer] Decode chunk error:", e)
+          decodeErrors++
+          console.warn(`[useCanvasPlayer] Decode chunk error (${decodeErrors}):`, e)
+          // 连续 3 次解码失败，放弃当前片段
+          if (decodeErrors >= 3) {
+            console.error("[useCanvasPlayer] Too many decode errors, aborting segment")
+            break
+          }
         }
       }
       console.log(
-        `[useCanvasPlayer] Segment ${meta.assetId}: decoded ${decodedCount}, skipped ${skippedCount}, decoder.state=${decoder.state}`,
+        `[useCanvasPlayer] Segment ${meta.assetId}: decoded ${decodedCount}, skipped ${skippedCount}, errors ${decodeErrors}, decoder.state=${decoder.state}`,
       )
 
-      // flush 超时保护：10秒
-      try {
-        await Promise.race([
-          decoder.flush(),
-          new Promise((_, reject) =>
-            setTimeout(() => reject(new Error("flush timeout 10s")), 10_000),
-          ),
-        ])
-        console.log(`[useCanvasPlayer] Segment ${meta.assetId}: flush complete`)
-      } catch (e) {
-        console.warn("[useCanvasPlayer] Decoder flush error:", e)
+      // flush 仅在解码器状态正常时执行
+      if (decoder.state === "configured") {
+        try {
+          await decoder.flush()
+          console.log(`[useCanvasPlayer] Segment ${meta.assetId}: flush complete`)
+        } catch (e) {
+          console.warn("[useCanvasPlayer] Decoder flush error:", e)
+        }
       }
     },
     [],