UI细节优化: 间距令牌、字体统一、LazyList key

- LumaComponents: LumaSettingRow/LumaPageTopBar 间距改用LumaSpacing令牌
- LumaComponents: LumaSettingRow标题fontSize改用LumaTypography.body
- HomeScreen: SectionTitle ExtraBold→Bold统一, MyMediaGrid LazyRow添加key
- VideoPlayerScreen: 播放器剧集列表LazyColumn添加key

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

app/src/main/kotlin/com/example/myapplication/screens/HomeScreen.kt

@@ -676,7 +676,7 @@ private fun SectionTitle(
         verticalAlignment = Alignment.CenterVertically,
         horizontalArrangement = Arrangement.SpaceBetween,
     ) {
-        Text(text = title, color = homeContentColor(), fontSize = 18.sp, fontWeight = FontWeight.ExtraBold)
+        Text(text = title, color = homeContentColor(), fontSize = 18.sp, fontWeight = FontWeight.Bold)
         if (count > 0) {
             Box(
                 Modifier
@@ -701,7 +701,7 @@ private fun MyMediaGrid(libraries: List<EmbyMediaFolder>, serverUrl: String, onS
     Column(verticalArrangement = Arrangement.spacedBy(8.dp)) {
         SectionTitle(title = stringResource(Res.string.section_library))
         LazyRow(horizontalArrangement = Arrangement.spacedBy(12.dp)) {
-            items(libraries) { folder ->
+            items(libraries, key = { it.id }) { folder ->
                 Column(
                     Modifier.width(176.dp),
                     horizontalAlignment = Alignment.CenterHorizontally,
@@ -866,7 +866,7 @@ private fun RainbowNumber(
                 LumaColors.rainbowGradient
             ),
             fontSize = fontSize,
-            fontWeight = FontWeight.ExtraBold,
+            fontWeight = FontWeight.Bold,
             textAlign = TextAlign.Center,
         ),
         maxLines = 1,

app/src/main/kotlin/com/example/myapplication/screens/VideoPlayerScreen.kt

@@ -1184,7 +1184,7 @@ fun VideoPlayerScreen(
                         )
                     } else {
                         LazyColumn(verticalArrangement = Arrangement.spacedBy(8.dp)) {
-                            items(items = episodes) { ep ->
+                            items(items = episodes, key = { it.id }) { ep ->
                                 LiquidEpisodeItem(
                                     episode = ep,
                                     serverUrl = serverUrl,

app/src/main/kotlin/com/example/myapplication/ui/design/LumaComponents.kt

@@ -356,7 +356,7 @@ fun LumaSettingRow(
                 role = Role.Button,
                 onClick = onClick,
             )
-            .padding(horizontal = LumaSpacing.md, vertical = 14.dp),
+            .padding(horizontal = LumaSpacing.md, vertical = LumaSpacing.sm),
         verticalAlignment = Alignment.CenterVertically,
     ) {
         Box(
@@ -373,12 +373,12 @@ fun LumaSettingRow(
                 modifier = Modifier.size(20.dp),
             )
         }
-        Spacer(Modifier.width(14.dp))
+        Spacer(Modifier.width(LumaSpacing.sm))
         Column(Modifier.weight(1f)) {
             Text(
                 title,
                 color = LumaColors.text,
-                fontSize = 15.sp,
+                fontSize = LumaTypography.body,
                 fontWeight = FontWeight.SemiBold,
             )
             if (subtitle.isNotEmpty()) {
@@ -413,7 +413,7 @@ fun LumaPageTopBar(
         modifier
             .fillMaxWidth()
             .statusBarsPadding()
-            .padding(horizontal = 18.dp, vertical = 14.dp),
+            .padding(horizontal = LumaSpacing.md, vertical = LumaSpacing.sm),
         verticalAlignment = Alignment.CenterVertically,
     ) {
         LumaIconButton(