feat: add sort options to Downloads screen

[lesquel]

Summary

Add the ability to sort downloaded songs by multiple criteria with ascending/descending direction. The sort preference persists between sessions.

Sort Options

Option	Description
Newest first	Download date, most recent first (default — current behavior)
Oldest first	Download date, oldest first
Title (A-Z)	Alphabetical by song title
Title (Z-A)	Reverse alphabetical by song title
Artist (A-Z)	Alphabetical by artist name
Artist (Z-A)	Reverse alphabetical by artist name

Implementation Details

Architecture

• No changes to core submodule — all new code lives in composeApp
• Follows the same MVVM + StateFlow + Compose patterns used throughout the app
• Reuses the visual style of SortPlaylistBottomSheet from LocalPlaylistScreen

New Files

• DownloadSortType.kt — Sealed class with 6 sort variants + serialization (toKey()/fromKey())

Modified Files

• LibraryDynamicPlaylistViewModel.kt — Reactive sorting via combine(rawSongs, sortType), preference persistence via DataStoreManager.putString()/getString()
• LibraryDynamicPlaylistScreen.kt — Sort icon button in TopAppBar (visible only for Downloaded type), SortDownloadsBottomSheet integration
• ModalBottomSheet.kt — New SortDownloadsBottomSheet composable
• AllExt.kt — DownloadSortType.displayNameRes() extension function
• 26 strings.xml files — i18n support for all existing locales (ar, az, bg, ca, de, es, fa, fi, fr, hi, in, it, iw, ja, ko, nl, pl, pt, ru, th, tr, uk, vi, zh, zh-rTW)

Key Design Decisions

• DownloadSortType is separate from FilterState (avoids modifying core submodule)
• DataStoreManager injected via by inject() from KoinComponent (no DI module changes needed)
• Client-side sorting (in-memory) — appropriate for typical download list sizes
• Sort preference key: "download_sort_type"

Screenshots

Sort icon appears in the Downloads screen TopAppBar. Tapping opens a bottom sheet with 6 sort options.

Testing Checklist

• Navigate to Library → Downloaded → sort icon is visible
• Each sort option reorders the list correctly
• Sort preference persists after leaving and returning to the screen
• Search works correctly with any active sort order
• Empty download list doesn't crash
• Songs without artist name sort correctly (fallback to empty string)

[slynobody]

highly second that to be merged soon, had the same idea.

[slynobody]

issue: advertised funcionality: 'Caching and offline playback' (main page) not working

• Context: app used offline (WiFi/Mobile data disabled) with downloaded playlists.
• Reproduce Issue: go offline, switch to 'library' / 'downloaded playlists', choose album

  black screen, no direct cache display (hanging while trying to fetch data online)

• Symptom: Music playback works, but navigating 'back' results in black screens continuing to load indefinitely.
• ui: Album covers seemingly missing in-app , though they appear correctly in the One UI 6.0 notification panel.
• workaround: inside 'library' / 'downloaded playlists' press album > black screen > navigate back (iterate): album show up randomly (sometimes 3-4x back, sometimes 5-8 times), data is there but not handled right in this context.

also see this 2 year old reddit-issue usablity of caches inside downloaded playlists (reddit, not fixed)
also see: #1604 #1292 #1753 #1750 #1576

if you dont want to fix this, please at least give hints on compiling source (link on main page).