Add resizable compact desktop player mode

[Copinmalin]

Summary

• add a compact-player toggle that keeps only the title bar and playback controls visible
• resize the native Tauri window to an 84 px compact height while keeping its width resizable from 560 px up to the active screen width
• preserve and restore the previous window size, position, and maximized state
• add localized labels for all ten supported languages
• cover compact layout, resizing bounds, and restoration in browser tests

Testing

• npm run build
• npm run check
• npm run i18n:check
• npm run test:unit (25 passed)
• npm run test:browser (45 passed)
• cargo test --manifest-path src-tauri/Cargo.toml --locked (61 passed, 2 network-dependent tests ignored)