cascade-upgrade-omega-v1 — balanced flagship

The safe king-challenger. Combines all three lineages on the proven cascade-v19 family mixture:

• ① core: the full causal cascade prior (trend/seasonal/AR, regimes, multiplicative Weibull, corrected AR(2), structured integrated, SETAR, chaotic, OU stochastic vol, physical sensors, NB seasonal counts, stateful intermittent, Hawkes pulses, cascade9 drift), prefix-512 standardization, and the producer-thread prefetch.
• ② speed + demand: numpy-only block-scan AR(1) everywhere, and the validated 8% weekly-demand family.
• ③ diversity: a modest 3% GARCH(1,1) volatility slice.
• turn-back fix: non-circular 2L spectral GP / long memory (keeps cascade9's broad winning prior, removes the endpoint-adjacency artifact v19 re-introduced).

Config highlights: chunk 2048, davies_harte_frac 0.0 (broad prior, no exact fGn), per_series_scale false. See ../README.md for the full rationale and the turn-back investigation.