_writeDouble

private fnvoid _writeDouble(W)(double d, ref W buf) @safe

Write a double value in RFC 8259 compliant format.

Uses %.17g format to ensure consistent, portable output that preserves full double precision. This avoids platform-dependent variations from to!string (e.g., capital 'E', variable exponent notation).

Parameters

`d`	The double value to write.
`buf`	The output buffer to write to.