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/styles/components.css

@@ -9190,17 +9190,47 @@ html.no-compositing .fsr-lyric-line.fsrl-active .fsr-lyric-word.active {
   justify-content: flex-end;
 }
 
-.mini-queue {
+.mini-queue-wrap {
   grid-column: 1 / -1;
   grid-row: 3;
-  overflow-y: auto;
-  overscroll-behavior: contain;
+  position: relative;
   background: var(--bg-card);
   border-radius: 8px;
+  overflow: hidden;
+  min-height: 0;
+}
+
+.mini-queue {
+  height: 100%;
+  overflow-y: auto;
+  overscroll-behavior: contain;
   padding: 4px;
   display: flex;
   flex-direction: column;
   gap: 1px;
+  box-sizing: border-box;
+  /* Hide native scrollbar — we render an overlay thumb beside it. */
+  scrollbar-width: none;
+}
+.mini-queue::-webkit-scrollbar {
+  display: none;
+}
+
+.mini-queue__thumb {
+  position: absolute;
+  top: 4px;
+  right: 3px;
+  width: 4px;
+  border-radius: 2px;
+  background: var(--text-muted);
+  opacity: 0;
+  transition: opacity 0.18s ease;
+  pointer-events: none;
+  will-change: transform;
+}
+.mini-queue-wrap:hover .mini-queue__thumb,
+.mini-queue.is-scrolling ~ .mini-queue__thumb {
+  opacity: 0.55;
 }
 
 .mini-queue__empty {
@@ -9228,6 +9258,14 @@ html.no-compositing .fsr-lyric-line.fsrl-active .fsr-lyric-word.active {
   background: var(--bg-hover);
 }
 
+.mini-queue__item--ctx {
+  background: var(--bg-hover);
+}
+
+.mini-queue-wrap--drop-active .mini-queue {
+  scroll-behavior: auto;
+}
+
 .mini-queue__item--current {
   background: var(--accent-dim);
   color: var(--accent);