fix(claude): recognize and pass through native Haiku helpers

Claude Code issues measured Haiku helper requests that intentionally omit the
claude-code beta and, for the minimal shape, the system field. Treat those
profiles as confirmed native clients so CPA does not cloak or rewrite them.

Accept the native metadata builder optional parent_session_id, require
platform headers only for presence and software baseline rather than exact
equality, derive timeout and version from the same header defaults the emitter
uses, and keep discriminating signals strict: exact beta allowlist, body
shape, lowercase hex CCH, and session binding. Preserve helper transport
headers, omit synthetic stream false on markerless helpers, and gate the
billing and CCH fallback on system presence so a later pipeline-attached system
prompt cannot go upstream unsigned while the measured no-system wire stays
intact.