feat(mini-player): persistent geometry, queue DnD + context menu, overlay scrollbar, live theme sync

This iteration fills in the pieces that make the mini player usable as a
daily standalone window:

- Window position persists to <app_config_dir>/mini_player_pos.json on
  every WindowEvent::Moved (throttled 250 ms); first launch lands in the
  bottom-right of the main window's monitor.
- Queue keeps a 260 px floor when expanded (~2 visible rows). The
  user-resized expanded height is restored on next toggle via
  localStorage so reopening doesn't snap back to the default 440 px.
- set_mini_player_always_on_top(true) now forces a false-then-true cycle
  so the WM re-evaluates the layer after a hide/show; the frontend also
  re-asserts the pin state on mount and on window focus, so the user no
  longer has to click the pin button twice for it to stick.
- Native scrollbar in the queue is hidden in favour of a JS-driven
  overlay thumb so items use the full width of the queue area.
- PsyDnD reorder works inside the mini queue: drag emits 'mini:reorder',
  the bridge calls reorderQueue on the source-of-truth store in main.
- Localized queue-item context menu (MiniContextMenu) with Play now /
  Remove from queue / Open album / Go to artist / Favorite / Song info.
  Cross-window actions forward to main via new bridge events
  (mini:reorder, mini:remove, mini:navigate, mini:song-info); a
  psy:navigate CustomEvent picked up by AppShell handles routing.
- Theme, font and language changes in main propagate live to the mini
  via a 'storage' event listener that re-hydrates the persisted Zustand
  stores and calls i18n.changeLanguage.

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

src/components/MiniContextMenu.tsx

@@ -0,0 +1,122 @@
+import { useEffect, useRef, useState } from 'react';
+import { createPortal } from 'react-dom';
+import { emit } from '@tauri-apps/api/event';
+import { useTranslation } from 'react-i18next';
+import { Play, Trash2, Disc3, User, Heart, Info } from 'lucide-react';
+import { star, unstar } from '../api/subsonic';
+import type { MiniTrackInfo } from '../utils/miniPlayerBridge';
+
+interface Props {
+  x: number;
+  y: number;
+  track: MiniTrackInfo;
+  index: number;
+  onClose: () => void;
+}
+
+/**
+ * Slim queue-item context menu for the mini player. The mini lives in its
+ * own webview, so all queue mutations forward to the main window via Tauri
+ * events; only the favorite call hits Subsonic directly because it has no
+ * cross-window state to keep in sync (next mini:sync from main reflects the
+ * new starred flag).
+ */
+export default function MiniContextMenu({ x, y, track, index, onClose }: Props) {
+  const { t } = useTranslation();
+  const ref = useRef<HTMLDivElement>(null);
+  const [starred, setStarred] = useState(!!track.starred);
+  const [pos, setPos] = useState({ left: x, top: y });
+
+  // Clamp the menu inside the mini window's viewport (it pops near the
+  // cursor and would otherwise overflow at the right/bottom edges of the
+  // small window).
+  useEffect(() => {
+    const el = ref.current;
+    if (!el) return;
+    const r = el.getBoundingClientRect();
+    const vw = window.innerWidth;
+    const vh = window.innerHeight;
+    const left = Math.min(x, Math.max(4, vw - r.width - 4));
+    const top = Math.min(y, Math.max(4, vh - r.height - 4));
+    setPos({ left, top });
+  }, [x, y]);
+
+  // Dismiss on outside click + Escape.
+  useEffect(() => {
+    const onDown = (e: MouseEvent) => {
+      if (ref.current && !ref.current.contains(e.target as Node)) onClose();
+    };
+    const onKey = (e: KeyboardEvent) => { if (e.key === 'Escape') onClose(); };
+    document.addEventListener('mousedown', onDown);
+    document.addEventListener('keydown', onKey);
+    return () => {
+      document.removeEventListener('mousedown', onDown);
+      document.removeEventListener('keydown', onKey);
+    };
+  }, [onClose]);
+
+  const run = (fn: () => void | Promise<void>) => {
+    Promise.resolve(fn()).finally(onClose);
+  };
+
+  const toggleStar = async () => {
+    const next = !starred;
+    setStarred(next);
+    try {
+      if (next) await star(track.id, 'song');
+      else await unstar(track.id, 'song');
+    } catch {
+      setStarred(!next);
+    }
+  };
+
+  return createPortal(
+    <div
+      ref={ref}
+      className="context-menu mini-context-menu"
+      style={{ position: 'fixed', left: pos.left, top: pos.top, zIndex: 99998 }}
+      onClick={(e) => e.stopPropagation()}
+      onContextMenu={(e) => e.preventDefault()}
+    >
+      <div className="context-menu-item" onClick={() => run(() => emit('mini:jump', { index }))}>
+        <Play size={14} /> {t('contextMenu.playNow')}
+      </div>
+      <div
+        className="context-menu-item"
+        style={{ color: 'var(--danger)' }}
+        onClick={() => run(() => emit('mini:remove', { index }))}
+      >
+        <Trash2 size={14} /> {t('contextMenu.removeFromQueue')}
+      </div>
+      <div className="context-menu-divider" />
+      {track.albumId && (
+        <div
+          className="context-menu-item"
+          onClick={() => run(() => emit('mini:navigate', { to: `/album/${track.albumId}` }))}
+        >
+          <Disc3 size={14} /> {t('contextMenu.openAlbum')}
+        </div>
+      )}
+      {track.artistId && (
+        <div
+          className="context-menu-item"
+          onClick={() => run(() => emit('mini:navigate', { to: `/artist/${track.artistId}` }))}
+        >
+          <User size={14} /> {t('contextMenu.goToArtist')}
+        </div>
+      )}
+      <div className="context-menu-item" onClick={() => run(toggleStar)}>
+        <Heart size={14} fill={starred ? 'currentColor' : 'none'} />
+        {starred ? t('contextMenu.unfavorite') : t('contextMenu.favorite')}
+      </div>
+      <div className="context-menu-divider" />
+      <div
+        className="context-menu-item"
+        onClick={() => run(() => emit('mini:song-info', { id: track.id }))}
+      >
+        <Info size={14} /> {t('contextMenu.songInfo')}
+      </div>
+    </div>,
+    document.body,
+  );
+}