Parent

• #402 Acquire word-timed lyrics from AMLL, then fall back to LRCLIB
• #403 Keep the list lyrics stage and show supplied romanization

What to build

Expand the lyrics types so a line can carry optional Supplied Romanization and a winning source can be amll. Existing lyrics behavior does not change. After this ticket, later tickets can persist AMLL wins and show supplied romanization without touching every constructor again.

Acceptance criteria

• The lyrics payload line type includes optional roman, always serialized, null when absent, same style as section.
• The lyrics source enum includes amll in both the IPC contract and the cache serializer, without renaming the historical lrclib / lrc_lib split.
• All existing lyric construction sites compile with roman defaulting to null and no new source behavior.
• The lyrics contract tables list roman and amll in the same change as the types.
• Existing lyrics tests and IPC contract tests pass, including the new source/field cases.

Blocked by

• None — can start immediately.