Add native MPRIS support on Linux

[BlueManCZ]

Summary

• Replace WebKitGTK's built-in navigator.mediaSession MPRIS integration with a native Rust implementation using the mpris-server crate
• The player now appears as museeks in playerctl -l instead of org.webkit.app-<hash>.Sandboxed.instance-<N>
• On Linux, audio playback uses the Web Audio API instead of <audio> element to prevent WebKitGTK's MPRIS entry from reporting active playback status
• macOS/Windows continue to use navigator.mediaSession

MPRIS features supported

• Play, pause, play/pause, stop, next, previous
• Shuffle (get/set)
• Loop status (None/Track/Playlist)
• Volume (get/set, with perceptual scaling matching the UI slider)
• Seek (absolute and relative)
• Position tracking
• Track metadata (title, artist, album, track number, duration, cover art)

Changes

Backend (Rust)

• New: src-tauri/src/plugins/mpris.rs — Native MPRIS server plugin using mpris-server crate with bidirectional IPC
• Modified: src-tauri/src/plugins/stream_server.rs — Added CORS header for Web Audio API fetch() compatibility
• Modified: src-tauri/src/libs/events.rs — Added PlaybackSeekTo, PlaybackSeekBy, PlaybackSetVolume,
  PlaybackSetShuffle, PlaybackSetRepeat IPC events

Frontend (TypeScript)

• New: src/lib/bridge-mpris.ts — IPC bridge for MPRIS commands (no-op on non-Linux)
• New: src/lib/web-audio-element.ts — Drop-in HTMLAudioElement replacement using AudioContext so WebKitGTK's MPRIS
  entry stays inactive
• Modified: src/lib/player.ts — Uses WebAudioElement on Linux, syncs state to native MPRIS, adds
  setShuffle/setRepeat methods
• Modified: src/lib/utils-player.ts — Extracted shared volume smoothing helpers
• Modified: src/components/VolumeControl.tsx — Uses shared volume smoothing helpers
• Modified: src/components/IPCPlayerEvents.tsx — Handles new MPRIS-originated events (seek, volume, shuffle, repeat)

Test plan

• playerctl -l shows museeks (the org.webkit.app-... entry may exist but stays in Stopped status)
• playerctl metadata shows title, artist, album, artUrl, length
• playerctl play, pause, play-pause, next, previous, stop
• playerctl shuffle On / Off
• playerctl loop None / Track / Playlist
• playerctl volume 0.5 sets the UI slider to 50%
• playerctl position 30 (absolute) and playerctl position 10+ (relative)
• Desktop environment media controls (GNOME/KDE) work
• App builds and runs on macOS/Windows (MPRIS code is cfg-gated, mediaSession still works)

[martpie]

oof. Thanks for this, but not sure how I feel about it, this is a lot of code specific to Linux.

I'll check is there are easier way to solve the issues you mentioned. If not, then I'll check this PR again.