refactor(mini-player): H6 — split MiniPlayer.tsx 820 → 218 LOC across 11 files (#669)

* refactor(mini-player): H6 — extract helpers + constants

Pure code-move: window-size constants, localStorage keys + read helpers,
toMini track shape, initialSnapshot, and fmt(seconds) → utils/miniPlayerHelpers.ts.

MiniPlayer.tsx: 820 → 745 LOC.

* refactor(mini-player): H6 — extract MiniTitlebar + MiniMeta + MiniControls

Three small visual subcomponents move into components/miniPlayer/.
MiniPlayer drops the now-unused Pin/PinOff/Maximize2/X/Play/Pause/
SkipBack/SkipForward lucide icons and the CachedImage import.

MiniPlayer.tsx: 745 → 665 LOC.

* refactor(mini-player): H6 — extract MiniToolbar + useMiniVolumePopover

The whole toolbar (volume button + portaled popover, shuffle, gapless/
crossfade/infinite, queue toggle) moves into MiniToolbar.tsx. The volume
popover open-state + ref/style positioning + outside-click/Escape close
move into the useMiniVolumePopover hook.

MiniPlayer.tsx: 665 → 492 LOC.

* refactor(mini-player): H6 — extract MiniQueue + useMiniQueueDrag

The OverlayScrollArea + queue.map block moves into MiniQueue.tsx. The
PsyDnD wiring (drop-inside emits mini:reorder, drop-outside emits
mini:remove, reorder math collapsing same-position + adjusting for shift)
moves into the useMiniQueueDrag hook.

MiniPlayer.tsx: 492 → 346 LOC.

* refactor(mini-player): H6 — extract useMiniSync + useMiniWindowSetup + useMiniKeyboardShortcuts

Three more hooks pull the remaining side-effect islands out of MiniPlayer:
  - useMiniSync owns mini:ready emit on mount + focus, plus the
    mini:sync / audio:progress / audio:ended listeners. The hidden-window
    visibility ref that gates progress now lives inside the hook.
  - useMiniWindowSetup bundles three small window-bound effects:
    Linux WebKitGTK smooth-scroll, the cold-start expanded-size restore
    when queueOpen=true, and always-on-top reapply on mount + focus.
  - useMiniKeyboardShortcuts moves the keyboard-shortcut bridge wiring.

MiniPlayer.tsx: 346 → 218 LOC.

src/components/miniPlayer/MiniMeta.tsx

@@ -0,0 +1,41 @@
+import CachedImage from '../CachedImage';
+import type { MiniTrackInfo } from '../../utils/miniPlayerBridge';
+
+interface Props {
+  track: MiniTrackInfo | null;
+  miniCoverSrc: string;
+  miniCoverKey: string;
+}
+
+export function MiniMeta({ track, miniCoverSrc, miniCoverKey }: Props) {
+  return (
+    <div className="mini-player__meta">
+      <div className="mini-player__art">
+        {track?.coverArt ? (
+          <CachedImage
+            src={miniCoverSrc}
+            cacheKey={miniCoverKey}
+            alt={track.album}
+          />
+        ) : (
+          <div className="mini-player__art-fallback" />
+        )}
+      </div>
+
+      <div className="mini-player__meta-text" data-tauri-drag-region="false">
+        <div className="mini-player__title" title={track?.title}>
+          {track?.title ?? '—'}
+        </div>
+        {track?.artist && (
+          <div className="mini-player__artist" title={track.artist}>{track.artist}</div>
+        )}
+        {track?.album && (
+          <div className="mini-player__album" title={track.album}>{track.album}</div>
+        )}
+        {track?.year && (
+          <div className="mini-player__year">{track.year}</div>
+        )}
+      </div>
+    </div>
+  );
+}