chore(lyrics): rename springScroll.ts to easeScroll.ts

After PR #214 replaced SpringScroller with EaseScroller, the filename
no longer matched the exported class. Rename for clarity.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/FullscreenPlayer.tsx

@@ -13,7 +13,7 @@ import { useLyrics, type WordLyricsLine } from '../hooks/useLyrics';
 import { useAuthStore } from '../store/authStore';
 import type { LrcLine } from '../api/lrclib';
 import type { Track } from '../store/playerStore';
-import { EaseScroller, targetForFraction } from '../utils/springScroll';
+import { EaseScroller, targetForFraction } from '../utils/easeScroll';
 
 function formatTime(seconds: number): string {
   if (!seconds || isNaN(seconds)) return '0:00';

src/components/LyricsPane.tsx

@@ -6,7 +6,7 @@ import { useLyrics, type WordLyricsLine } from '../hooks/useLyrics';
 import { useAuthStore } from '../store/authStore';
 import { useTranslation } from 'react-i18next';
 import type { Track } from '../store/playerStore';
-import { EaseScroller, targetForFraction } from '../utils/springScroll';
+import { EaseScroller, targetForFraction } from '../utils/easeScroll';
 
 interface Props {
   currentTrack: Track | null;