widenClassFile

The overlay's bytes for one class, for every producer of it — the shard writer and the mixin graft alike.

Renames only what actually names a Minecraft class: the scan is a memcmp against the parse it saves, and it keeps every MC-free class (and every class on a non-renaming runtime) on the copy path. Total by design — a class that needs no change, or that cannot be parsed, comes back as its own bytes, so a caller never has to decide what "no result" means.