fix: lyrics scroll — center active line only, remove drift phase

The 'drift to next line' animation moved the text while the user was
still reading/singing the current line, making it feel out of sync.
Now matches the web behavior: smooth-scroll to center the active line
when it changes, nothing more.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

android/app/src/main/kotlin/com/novasonic/app/ui/screen/NowPlayingScreen.kt

@@ -411,21 +411,12 @@ fun NowPlayingScreen(
                     lyricsState.lines.indexOfLast { it.timeMs <= state.positionMs + 200L }.coerceAtLeast(0)
                 else -1
 
-                // Smooth continuous scroll: snap to active line, then drift toward the next
+                // Center the active line when it changes — matches web behavior (no drift)
                 LaunchedEffect(activeIdx) {
                     if (activeIdx < 0 || lyricsState.lines.isEmpty() || lyricsViewH == 0) return@LaunchedEffect
-
-                    fun targetFor(idx: Int) = (lyricsPaddingPx + idx * lineHeightPx + lineHeightPx / 2f
-                        - lyricsViewH * 0.30f).coerceAtLeast(0f).toInt()
-
-                    // Phase 1: snap to the active line
-                    lyricsScrollState.animateScrollTo(targetFor(activeIdx), tween(380, easing = FastOutSlowInEasing))
-
-                    // Phase 2: drift to the next line's position over this line's remaining duration
-                    val nextLine = lyricsState.lines.getOrNull(activeIdx + 1) ?: return@LaunchedEffect
-                    val thisLine = lyricsState.lines[activeIdx]
-                    val driftMs  = (nextLine.timeMs - thisLine.timeMs - 380L).coerceIn(50L, 12_000L)
-                    lyricsScrollState.animateScrollTo(targetFor(activeIdx + 1), tween(driftMs.toInt(), easing = LinearEasing))
+                    val target = (lyricsPaddingPx + activeIdx * lineHeightPx + lineHeightPx / 2f
+                        - lyricsViewH * 0.5f).coerceAtLeast(0f).toInt()
+                    lyricsScrollState.animateScrollTo(target, tween(350, easing = FastOutSlowInEasing))
                 }
 
                 when {