fix: resolve playroom UI state inconsistency when page loses focus

When lyrics are enabled and the page loses focus while playing a song without lyrics,
then plays a song with lyrics, returning to the page caused controller and lyrics
layout to become misaligned. Added page focus handlers to sync UI state correctly.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/components/ScrollingLyrics.vue

@@ -543,8 +543,39 @@ watch(() => props.lrcSrc, async (newSrc) => {
 	}
 }, { immediate: true })
 
+
+// 页面焦点处理函数变量声明
+let handleVisibilityChange: (() => void) | null = null
+
+// 页面焦点处理
+function setupPageFocusHandlers() {
+	handleVisibilityChange = () => {
+		if (document.hidden) {
+			// 页面失去焦点时暂停动画
+			if (scrollTween) scrollTween.pause()
+			if (highlightTween) highlightTween.pause()
+		} else {
+			// 页面重新获得焦点时恢复并重新同步
+			if (scrollTween && scrollTween.paused()) scrollTween.resume()
+			if (highlightTween && highlightTween.paused()) highlightTween.resume()
+			
+			// 重新同步歌词位置
+			nextTick(() => {
+				if (currentLineIndex.value >= 0 && autoScroll.value && !userScrolling.value) {
+					scrollToLine(currentLineIndex.value, false) // 不使用动画，直接定位
+				}
+			})
+		}
+	}
+
+	document.addEventListener('visibilitychange', handleVisibilityChange)
+}
+
 // 组件挂载时的入场动画
 onMounted(() => {
+	// 设置页面焦点处理
+	setupPageFocusHandlers()
+
 	// 控制面板入场动画
 	if (controlPanel.value) {
 		gsap.fromTo(controlPanel.value,
@@ -577,6 +608,11 @@ onUnmounted(() => {
 	if (scrollTween) scrollTween.kill()
 	if (highlightTween) highlightTween.kill()
 	if (userScrollTimeout) clearTimeout(userScrollTimeout)
+	
+	// 清理页面焦点事件监听器
+	if (handleVisibilityChange) {
+		document.removeEventListener('visibilitychange', handleVisibilityChange)
+	}
 })
 
 // 暴露方法给父组件

src/pages/Playroom.vue

@@ -83,6 +83,9 @@ onMounted(async () => {
 	thumbUpdate()
 
 	setupEntranceAnimations()
+
+	// 添加页面焦点事件监听
+	setupPageFocusHandlers()
 })
 
 function timeFormatter(time: number) {
@@ -419,9 +422,98 @@ watch(() => [preferences.presentLyrics, getCurrentTrack()?.song.lyricUrl], (newV
 	}
 }, { immediate: true })
 
+// 页面焦点处理函数变量声明
+let handleVisibilityChange: (() => void) | null = null
+let handlePageFocus: (() => void) | null = null
+
 onUnmounted(() => {
+	// 清理页面焦点事件监听器
+	if (handleVisibilityChange) {
+		document.removeEventListener('visibilitychange', handleVisibilityChange)
+	}
+	if (handlePageFocus) {
+		window.removeEventListener('focus', handlePageFocus)
+	}
 })
 
+// 页面焦点处理函数
+function setupPageFocusHandlers() {
+	handleVisibilityChange = () => {
+		if (document.hidden) {
+			// 页面失去焦点时，暂停所有动画
+			console.log('[Playroom] 页面失去焦点，暂停动画')
+		} else {
+			// 页面重新获得焦点时，重新同步状态
+			console.log('[Playroom] 页面重新获得焦点，同步状态')
+			nextTick(() => {
+				resyncLyricsState()
+			})
+		}
+	}
+
+	handlePageFocus = () => {
+		console.log('[Playroom] 窗口获得焦点，同步状态')
+		nextTick(() => {
+			resyncLyricsState()
+		})
+	}
+
+	// 监听页面可见性变化
+	document.addEventListener('visibilitychange', handleVisibilityChange)
+	window.addEventListener('focus', handlePageFocus)
+}
+
+// 重新同步歌词状态
+function resyncLyricsState() {
+	const currentTrack = getCurrentTrack()
+	if (!currentTrack) return
+
+	console.log('[Playroom] 重新同步歌词状态')
+
+	// 重置动画状态
+	if (controllerRef.value) {
+		gsap.set(controllerRef.value, { 
+			marginLeft: '0rem', 
+			marginRight: '0rem' 
+		})
+	}
+
+	if (lyricsSection.value) {
+		gsap.set(lyricsSection.value, { 
+			opacity: 1, 
+			x: 0, 
+			y: 0, 
+			scale: 1 
+		})
+	}
+
+	// 检查当前歌词显示状态应该是什么
+	const shouldShowLyrics = preferences.presentLyrics && currentTrack.song.lyricUrl ? true : false
+
+	if (shouldShowLyrics !== presentLyrics.value) {
+		console.log(`[Playroom] 歌词状态不一致，重新设置: ${presentLyrics.value} -> ${shouldShowLyrics}`)
+		
+		// 直接设置状态，不触发动画
+		presentLyrics.value = shouldShowLyrics
+		
+		// 如果需要显示歌词，重新执行显示动画
+		if (shouldShowLyrics) {
+			nextTick(() => {
+				const tl = gsap.timeline()
+				tl.from(controllerRef.value, {
+					marginRight: '-40rem',
+					duration: 0.4,
+					ease: "power2.out"
+				}).fromTo(lyricsSection.value,
+					{ opacity: 0, x: 50, scale: 0.95 },
+					{ opacity: 1, x: 0, scale: 1, duration: 0.5, ease: "power2.out" },
+					"-=0.2"
+				)
+			})
+		}
+	}
+}
+
 // New: Watch for track changes and animate
 watch(() => playQueueStore.currentIndex, () => {
 	if (albumCover.value) {