feat(ui): smooth 90Hz tab navigation, sleek circular sliders, infinite autoplay, and in-app updater

[fhes-tus]

Overview

This PR brings major UI fluidity, modern slider styling, and playback enhancements to LastWave:

1. Buttery-Smooth Tab Navigation & Reactive Dock (MainShell.kt)

• Problem: When swiping or switching tabs on 90Hz / 120Hz displays, horizontal transitions exhibited stutter due to cold first-frame composition (beyondViewportPageCount = 0) and delayed pill animations.
• Solution:
  • Enabled beyondViewportPageCount = 1 so adjacent screen layouts stay cached in GPU composition memory.
  • Bound the floating dock selection to pagerState.targetPage for instantaneous pill response on finger tap.
  • Tuned dock pill animation with non-oscillating ExpressiveMotion.smoothSpring().

2. Sleek Circular Slider Thumbs (ExpressiveSlider.kt & PlayerHost.kt)

• Problem: Seekbars and settings sliders previously used tall 38dp vertical bars and default Material rectangular capsules.
• Solution:
  • Redesigned the expanded player seekbar thumb into a sleek circular knob with depth halo and inner surface core.
  • Created reusable ExpressiveSlider (in ui/common/) featuring capsule tracks and dynamic halo expansion on drag/press, applied across Settings (EQ gain, volume, color pickers) and Generator.

3. YouTube-Music-Style Infinite Autoplay (MusicPlayer.kt)

• Problem: Music abruptly ended when an album or playlist finished.
• Solution:
  • Seamlessly extends ordinary playback queues with similar tracks via Last.fm API recommendations and Discover fallback.
  • Proactively queries for refills before the queue runs out, with fallback resumption if playback reached the end.
  • User-toggleable in Now Playing queue sheet and in Settings.

4. Full-Device Local Music Scanner (TrackDownloadManager.kt)

• Problem: The local library scanner previously only checked Music/LastWave%, ignoring user audio in other device folders (Music/, Download/, etc.).
• Solution:
  • Expanded MediaStore query to index all valid audio tracks (IS_MUSIC != 0) across device storage, filtering out short audio clips (<30s).
  • Added safety guards ensuring deleteDownloadedTrack only deletes physical files that LastWave owns, keeping personal user audio untouched.
  • Declared READ_MEDIA_AUDIO for Android 13+ with runtime permission checks.

5. In-App GitHub Auto-Updater (AppUpdateManager.kt & SettingsScreen.kt)

• Added direct GitHub release checking against Clash-Projects/LastWave-native/releases/latest.
• Displays current vs latest version badge, changelog dialog ("What's new"), and direct release/APK download in Settings.

---

Verification

• Tested and verified with ./gradlew compileDebugKotlin and ./gradlew assembleDebug (0 compiler warnings/errors, all native Oboe ABIs compiled).
• Tested on Android device with smooth 90 FPS tab scrolling.