feat(immersive): add real coverflow with queue navigation

- Rename old CoverflowPanel to StaticPanel (single artwork view)
- Create new CoverflowPanel with actual coverflow effect:
  - Shows 5 album covers (2 prev, current, 2 next)
  - 3D perspective rotation on side covers
  - Click on side covers to navigate queue
  - Smooth animation on track change
- Add 'static' tab to focus mode (4 tabs total)
- Update keyboard shortcuts: 1-4 for focus tabs

src/lib/components/immersive/ImmersiveHeader.svelte

@@ -1,10 +1,10 @@
 <script lang="ts">
-  import { Disc3, Mic2, ListMusic, Music2, Info, Radio, Maximize, Minimize, ChevronDown, X, Square, Copy, Minus } from 'lucide-svelte';
+  import { Disc3, Mic2, ListMusic, Music2, Info, Radio, Maximize, Minimize, ChevronDown, X, Square, Copy, Minus, Image } from 'lucide-svelte';
   import { t } from '$lib/i18n';
   import { getCurrentWindow } from '@tauri-apps/api/window';
 
   export type ImmersiveTab = 'lyrics' | 'trackInfo' | 'suggestions' | 'queue';
-  export type FocusTab = 'coverflow' | 'lyrics-focus' | 'queue-focus';
+  export type FocusTab = 'coverflow' | 'static' | 'lyrics-focus' | 'queue-focus';
   export type ViewMode = 'focus' | 'split';
 
   interface Props {
@@ -85,6 +85,7 @@
   // Focus mode tabs
   const focusTabs: { id: FocusTab; label: string; icon: typeof Disc3 }[] = [
     { id: 'coverflow', label: 'Coverflow', icon: Disc3 },
+    { id: 'static', label: 'Static', icon: Image },
     { id: 'lyrics-focus', label: 'Lyrics', icon: Mic2 },
     { id: 'queue-focus', label: 'Queue', icon: ListMusic },
   ];