parseCookie(header: string | null | undefined): Record<string, string>
Parses a Cookie request header into a name→value record.
Values are percent-decoded, mirroring serializeCookie's encoding
so that the two round-trip. A value that is not valid percent-encoding is
returned verbatim rather than throwing, because a malformed cookie is a
client concern. Pairs without = are skipped, and when a name repeats the
first occurrence wins — browsers send the most specific cookie first.