fix(lyrics): read sidecar lyrics and playlists that are not utf-8

docs/features/integrations.md

@@ -140,7 +140,7 @@ Triggered from [`emit_track_changed`](../../src-tauri/crates/app/src/commands/pl
 
 1. **Cache** — `app.lyrics` row keyed by `track.file_hash` (BLAKE3). Shared across profiles, kept for good — except a partial miss, which carries a `retry_after` date ([below](#which-providers-are-asked-for-which-tracks)).
 2. **Embedded** — `LYRICS` / `USLT` / `©lyr` tag in the file (lofty), incl. synced `LRC` blocks. Lookup tries `ItemKey::UnsyncLyrics` first (the only key that maps to ID3v2's `USLT` in lofty 0.24), then `ItemKey::Lyrics` for Vorbis / MP4. For MP3s tagged with Mp3tag / foobar2000 / lame `--tg`, lyrics often live in a TXXX user-defined frame named `LYRICS` or `UNSYNCEDLYRICS` (common on K-Pop / J-Pop rips); these are invisible to the generic `Tag` interface so [`commands/lyrics.rs::read_id3v2_txxx_lyrics`](../../src-tauri/crates/app/src/commands/lyrics.rs) re-opens the file as `MpegFile`, downcasts to `Id3v2Tag`, and scans the TXXX descriptions explicitly.
-3. **Sidecar file** — `{stem}.lrc` / `{stem}.txt` next to the audio file (e.g. `01 Song.mp3` + `01 Song.lrc`), or inside a sibling `Lyrics/` folder (case-insensitive, so `lyrics/` is also matched — common Linux convention). Stem matching is also case-insensitive so `Song.MP3` finds `song.lrc` on case-sensitive filesystems. `.lrc` wins over `.txt` at every probed directory because it carries timing info; same-folder hits beat `Lyrics/` hits. Format is auto-detected via `detect_format` and the row is cached with `source = lrc_file`. Whitespace-only files are treated as misses so the waterfall keeps falling through. Writing one is a choice: the destination below decides whether an edit — or a fetch — lands in the tag, in a sidecar or in the database alone.
+3. **Sidecar file** — `{stem}.lrc` / `{stem}.txt` next to the audio file (e.g. `01 Song.mp3` + `01 Song.lrc`), or inside a sibling `Lyrics/` folder (case-insensitive, so `lyrics/` is also matched — common Linux convention). Stem matching is also case-insensitive so `Song.MP3` finds `song.lrc` on case-sensitive filesystems. `.lrc` wins over `.txt` at every probed directory because it carries timing info; same-folder hits beat `Lyrics/` hits. Format is auto-detected via `detect_format` and the row is cached with `source = lrc_file`. The file need not be UTF-8 (#910): [`text_encoding::decode`](../../src-tauri/crates/core/src/text_encoding.rs) honours a byte-order mark (UTF-8, UTF-16), reads valid UTF-8 as it is, and only then guesses the encoding from the bytes (`chardetng`, decoded by `encoding_rs`), so lyrics saved as GB18030, Big5, Shift_JIS, EUC-KR or a Windows code page are read too. A fixed fallback would not do: GB18030 accepts almost any byte sequence, so a Japanese or Korean file would come back as Chinese-looking nonsense. A cached miss is checked against the sidecar before it is served (`read_cached_or_new_sidecar`): the cache is keyed by the audio's hash and a complete miss is kept for good, so a sidecar added after the miss — or one that was unreadable before #910 — would otherwise stay hidden behind it forever. The sidecar is the one local source that can change without that hash changing, and it outranks a miss in every order the waterfall runs; the check costs one directory listing, and only for tracks without lyrics. The sidecar is written over the miss only while the row still holds it, so lyrics a lookup or an edit stored in between are served instead. Whitespace-only files are treated as misses so the waterfall keeps falling through. Writing one is a choice: the destination below decides whether an edit — or a fetch — lands in the tag, in a sidecar or in the database alone.
 
 4. **Generic `description` field** — last of the local tiers, and the
    only one that is a guess about a field meant for something else.
@@ -197,7 +197,7 @@ The bulk `run_prefetch` gap-filler stays local-first regardless of the toggle: i
 
 The panel re-fetches per song — the sentinel track id stays constant for the whole session, so the effect keys on title + artist instead — and renders **statically**: synced LRC is timestamp-stripped, because the live stream position can't be aligned to a song that may have been joined mid-play. Library-row mutation actions (edit / import / refetch / clear) are hidden for radio.
 
-`import_lrc_file` is still available for the explicit "pick this file" flow (e.g. when the sidecar lives in a non-conventional location like `~/Documents/lyrics/`); it overwrites the cached row regardless of which tier filled it.
+`import_lrc_file` is still available for the explicit "pick this file" flow (e.g. when the sidecar lives in a non-conventional location like `~/Documents/lyrics/`); it decodes the file the same way as a sidecar, and overwrites the cached row regardless of which tier filled it.
 
 **In-app editor.** `save_lyrics(track_id, { content, format, write_to_file })` upserts the cache row with `source = manual` and, when `write_to_file` is true, also writes the content into the file's `USLT` (ID3v2) / `UNSYNCEDLYRICS` (Vorbis) / `©lyr` (MP4) frame via lofty. Same Windows file-lock dance as the tag editor — pause if the engine has the file open, then re-hash with blake3 and update `track.file_hash` so the cache row stays addressable after the write. Emits a typed `lyrics:updated` event the panel listens to.
 

docs/features/playlists.md

@@ -31,7 +31,7 @@ Drag-and-drop is implemented with `@dnd-kit` over a virtualised list (`@tanstack
 
 ## M3U import / export
 
-`export_playlist_m3u` writes a UTF-8 `.m3u8` with `#EXTINF:<duration>,<artist> - <title>` headers and absolute file paths, through a partial sibling of its own (created exclusively) renamed over the destination once complete ([`atomic_write`](../../src-tauri/crates/core/src/atomic_write.rs)), so overwriting an existing playlist file that fails halfway leaves the old one intact rather than truncated; a partial left by a write that never finished is removed by the next write to the same file once it is a day old. The importer accepts both `.m3u` and `.m3u8` (foobar2000, VLC, Rekordbox, hand-written sets) and matches against the active library:
+`export_playlist_m3u` writes a UTF-8 `.m3u8` with `#EXTINF:<duration>,<artist> - <title>` headers and absolute file paths, through a partial sibling of its own (created exclusively) renamed over the destination once complete ([`atomic_write`](../../src-tauri/crates/core/src/atomic_write.rs)), so overwriting an existing playlist file that fails halfway leaves the old one intact rather than truncated; a partial left by a write that never finished is removed by the next write to the same file once it is a day old. The importer accepts both `.m3u` and `.m3u8` (foobar2000, VLC, Rekordbox, hand-written sets), decoded like a lyrics sidecar ([`text_encoding`](../../src-tauri/crates/core/src/text_encoding.rs)) — a legacy `.m3u` is in the code page of the machine that wrote it, Windows-1252 as often as GBK or Shift_JIS — and matches against the active library:
 
 1. **Canonical-path match** — strip Windows `\\?\` prefix, lowercase the drive letter, normalise separators.
 2. **Basename fallback** — if path-match fails, try the basename. This recovers playlists exported before a library reorganisation.

packaging/flatpak/generated/cargo-sources.json

@@ -948,6 +948,19 @@
         "dest": "cargo/vendor/chacha20-0.10.2",
         "dest-filename": ".cargo-checksum.json"
     },
+    {
+        "type": "archive",
+        "archive-type": "tar-gzip",
+        "url": "https://static.crates.io/crates/chardetng/chardetng-1.0.0.crate",
+        "sha256": "13de944a44b5064ee5d3a5ceccc49a41bfec50f2580e66f82e87703acdb88b53",
+        "dest": "cargo/vendor/chardetng-1.0.0"
+    },
+    {
+        "type": "inline",
+        "contents": "{\"package\": \"13de944a44b5064ee5d3a5ceccc49a41bfec50f2580e66f82e87703acdb88b53\", \"files\": {}}",
+        "dest": "cargo/vendor/chardetng-1.0.0",
+        "dest-filename": ".cargo-checksum.json"
+    },
     {
         "type": "archive",
         "archive-type": "tar-gzip",

src-tauri/crates/app/Cargo.toml

@@ -297,6 +297,8 @@ same-file = "1"
 # (artwork extraction, folder cover fallback, etc.). Auto-cleaned on
 # Drop so a panicked test doesn't leak fixtures across the temp dir.
 tempfile = "3"
+# Writes a lyrics sidecar in a legacy encoding for the decoding test.
+encoding_rs = "0.8.42"
 
 # Linux-only: direct ALSA enumeration so the output-device picker can
 # show human-readable descriptions ("HDA Intel PCH, ALC897 Analog