feat(perf): 3-state animation mode (Full / Reduced / Static) (#441)

* feat(perf): 3-state animation mode (Full / Reduced / Static)

Replaces the boolean `reducedAnimations` toggle with a three-way
`animationMode` setting, suggested by Viktor Petrovich after the
Windows audio fix (PR #426) shipped and confirmed a measurable
GPU drop:

- `full` (default): native frame rate, marquee scrolls normally
- `reduced`: 30 fps cap on the animated seekbar wave; player
  marquee runs at half speed
- `static`: rAF loop disabled; the seekbar repaints from the
  ~2 Hz audio:progress heartbeat. Player title/artist truncate
  with ellipsis instead of scrolling.

Migration in `onRehydrateStorage` maps legacy
`reducedAnimations: true` to `'reduced'`, anything else to
`'full'`. Static is opt-in only.

Settings UI follows the ReplayGain Auto/Track/Album pattern with
a contextual hint that explains what each mode does.

i18n: 5 new keys across 8 locales, 2 legacy keys removed.

* docs(changelog): add #441 3-state animation mode entry

* chore(credits): add #441 to Psychotoxical contributions

src/components/MarqueeText.tsx

@@ -1,4 +1,5 @@
 import React, { useRef, useState, useEffect, useCallback } from 'react';
+import { useAuthStore } from '../store/authStore';
 
 interface Props {
   text: string;
@@ -11,6 +12,7 @@ export default function MarqueeText({ text, className, style, onClick }: Props)
   const containerRef = useRef<HTMLDivElement>(null);
   const textRef = useRef<HTMLSpanElement>(null);
   const [scrollAmount, setScrollAmount] = useState(0);
+  const animationMode = useAuthStore(s => s.animationMode);
 
   const measure = useCallback(() => {
     const container = containerRef.current;
@@ -30,17 +32,22 @@ export default function MarqueeText({ text, className, style, onClick }: Props)
     return () => ro.disconnect();
   }, [text, measure]);
 
+  // In `static` animation mode the marquee never scrolls — overflowing text
+  // is truncated with an ellipsis (handled by CSS via data-anim-mode).
+  const shouldScroll = scrollAmount > 0 && animationMode !== 'static';
+
   return (
     <div
       ref={containerRef}
       className={`marquee-wrap${className ? ` ${className}` : ''}`}
       style={style}
       onClick={onClick}
+      data-anim-mode={animationMode}
     >
       <span
         ref={textRef}
-        className={scrollAmount > 0 ? 'marquee-scroll' : ''}
-        style={scrollAmount > 0 ? { '--marquee-amount': `-${scrollAmount}px` } as React.CSSProperties : {}}
+        className={shouldScroll ? 'marquee-scroll' : ''}
+        style={shouldScroll ? { '--marquee-amount': `-${scrollAmount}px` } as React.CSSProperties : {}}
       >
         {text}
       </span>