Named literals now follow AllowReadingFromString and WriteAsString as
System.Text.Json's float does; quoted numbers refuse whitespace;
UnmappedMemberHandling.Disallow and AllowDuplicateProperties=false are honoured
and a repeated property replaces the whole value; dictionary keys read only the
canonical spelling. Components live in stack spans, property names are
pre-encoded, and there is no per-property closure, so a float3 read allocates
nothing (424 bytes before). Tests pin unknown nested values, de-DE and sv-SE
style cultures, and a distinct negative-zero key.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>