Add package-level documentation (doc.go) to all 22 first-party
packages and godoc comments to ~150 previously undocumented
exported symbols across common/, network/, and server/.
UTF8ToSJIS panicked when encountering characters outside the Shift-JIS
range (emoji, Lenny faces, cuneiform, etc.), crashing the server when
such characters were sent via the Discord relay channel.
Replace the panic with graceful filtering that drops unmappable runes
and preserves valid content. Also fix ToNGWord index-out-of-range panic
on empty encoder output.
Closes#116