Raw storage, log-stream header derivation, and auto-param detection
were inlined directly in the ingest actor's write closure alongside
metric computation. Pulling them into their own method gives the
ingest arm two clearly separated, independently-callable stages —
param extraction (ingest_params) and metric computation
(apply_all_metrics) — with no behavior change, in preparation for
splitting these onto separate actors (ticket 102).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TeyhRfMYjMditek6geDRoQ