feat: Waveform seekbar, MilkDrop visualizer, EQ bars, in-app browser, and UX improvements (v1.3.0)

- PlayerBar redesigned: canvas waveform seekbar (500 bars, blue→mauve gradient + glow) replaces thin slider; new flex layout; queue toggle moved to content header (consistent with sidebar pattern)
- MilkDrop visualizer in Ambient Stage via Butterchurn; hidden audio analysis, preset shuffle, smooth blend transitions
- Tracklist: animated EQ bars for playing track, play icon when paused, align-items: center fix
- Artist pages: Last.fm + Wikipedia open in native Tauri WebviewWindow (in-app browser)
- Hero/Discover deduplication: single fetch of 20 random albums split between sections
- Update checker: runs every 10 minutes during runtime; version shown without v-prefix
- Settings version: now read from package.json instead of hardcoded
- Help page: new Random Mix section, updated Playback + Library sections, improved accordion styling
- Bump version to 1.3.0

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/types/butterchurn.d.ts

@@ -0,0 +1,20 @@
+declare module 'butterchurn' {
+  interface Visualizer {
+    connectAudio(audioNode: AudioNode): void;
+    loadPreset(preset: unknown, blendTime: number): void;
+    render(): void;
+    setRendererSize(width: number, height: number): void;
+  }
+  interface CreateOptions {
+    width: number;
+    height: number;
+    pixelRatio?: number;
+  }
+  function createVisualizer(ctx: AudioContext, canvas: HTMLCanvasElement, opts: CreateOptions): Visualizer;
+  export default { createVisualizer };
+}
+
+declare module 'butterchurn-presets' {
+  function getPresets(): Record<string, unknown>;
+  export default { getPresets };
+}