* feat(lyrics): add Simplified Chinese translations
Ship translations/zh-Hans.json so the plugin UI follows Noctalia's
host language when set to Simplified Chinese.
* fix(lyrics): restore splayer in lyrics_sources help text
The i18n reorder dropped splayer from settings.lyrics_sources.description.
* feat(lyrics): add album artwork fallbacks
Use artwork returned by matched lyric sources when MPRIS artwork is missing
or fails, preserve detected image formats, and bound the cover cache.
