oil-prices enriched — second enrich rep settles the parallel-resources question

oil-prices moved structured → enriched, the second hand rep of the draft enrich skill (co2-ppm was the first). Its eight Brent/WTI series all share one measurement (Price), so this rep consolidates them into a single stats table keyed by resource + measurement instead of eight near-identical ones — resolving the "parallel resources" open question the skill draft left for exactly this case. The stats confirm the 2020-04-20 negative WTI spot price (-$36.98) survives the pipeline intact and washes out once averaged into the weekly/monthly/annual series, and that Brent and WTI both peaked on the same day, 2008-07-03. Along the way a stale view titled "Brent vs WTI" that only plotted one resource got split into two honest single-series views. enrich.ts ships with 19 tests covering empty/missing/zero/negative/constant inputs and byte-for-byte preservation of hand-written commentary across reruns.