Function encode_write_point 

pub fn encode_write_point(point: &Point) -> Result<Vec<u8>, CodecError>

Encode a single write-point directly without constructing a WalEntry.

This avoids the Point::clone() that would otherwise be needed to build a WalEntry::Write { point } variant. On the hot write path — especially batch inserts — this eliminates one String + Vec heap allocation per point.

Errors

Returns CodecError::Postcard when postcard serialization fails.