fix: tighten Media openLive opening lock around close and rejoin

src/views/MediaView/MediaView.vue

@@ -305,9 +305,10 @@ async function openLive(stream) {
     return
   }
 
+  opening = true
+  try {
     await closeActiveLive()
     if (disposed) return
-  opening = true
     const seq = ++openSeq
     try {
       const result = await joinLiveWithRetry(stream.dockId, {}, {
@@ -351,11 +352,13 @@ async function openLive(stream) {
     } catch (e) {
       if (seq !== openSeq || disposed || e?.code === 'ABORTED') return
       if (isLeaseInvalidError(e)) {
+        opening = false // unlock before nested openLive via rejoin
         await rejoinAfterLeaseInvalid(stream.id, stream.dockId)
         return
       }
       await closeActiveLive()
       ui.toast(e.message || '打开直播失败')
+    }
   } finally {
     opening = false
   }