calcEscapedLength looped from strlen(raw) down to 1, counting the
terminator instead of the first character. A value starting with a
character that needs escaping was counted one byte short, so the fit
check could let it be written one byte past the buffer. Control
characters other than \b\f\n\r\t were copied raw, which isn't valid
JSON.
Both now go through one escapeChar helper, which also escapes the
remaining control characters as \u00XX.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
JsonFormatter and BufferedJsonFormatter move verbatim out of
WResp.cpp/WResp.h, which now include JsonFormatter.h. They don't need
the web server, so on their own they can be unit tested on the PC; the
native env builds the new file. AsyncJsonResp and JsonSockEvent stay
in WResp. No behaviour change.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
