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-tauri/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "psysonic"
-version = "1.2.0"
+version = "1.3.0"
 description = "Psysonic Desktop Music Player"
 authors = []
 license = ""