MetroList: Copy All Lyrics Button

Problem

Users wanted to copy lyrics to clipboard for sharing or reference, but had to manually select text which was often imprecise with scrolling lyrics.

Solution

Added "Copy all lyrics" button to the lyrics display screen. Uses Material 3 FilledTonalButton with content_copy icon. Shows toast confirmation when lyrics are copied.

Result

One-tap lyrics copy with visual feedback. Better user experience for lyrics sharing.

Commit: MetrolistGroup/Metrolist@a38da83
PR: #3250