Add SJISToUTF8Lossy() that wraps SJISToUTF8() and logs decode errors at
slog.Debug level. Replace all 31 call sites across 17 files that previously
discarded the error with `_, _ =`. This makes garbled text from malformed
SJIS client data debuggable without adding noise at default log levels.
Verified via Wii U decompilation of putUpdate_house: the field is set
to 0 when no password is provided, and 1 when a password string is
present. The previous comment "Always 0x01" was inaccurate.