Relocates the TTML, SRT, and embedded-dispatch parsers (pure text ->
model.LyricList transforms) into package model, alongside the existing
ToLyrics (LRC/ELRC) and ParseLyricsfile parsers.
This removes the model/metadata -> core/lyrics import edge (a lower layer
depending on business logic), which was the only reason model imported
core. core/lyrics now contains only the source-priority + plugin service,
which is consumed solely by server/subsonic.
parseTTML/parseSRT are exported as ParseTTML/ParseSRT so the remaining
core/lyrics service can still call them across the package boundary.
917f16a96d