1. MSSA (15.75)
   Multivariate SSA for shared-structure decomposition across channels.
   reasons: maturity:flagship, native_backed, shared_multivariate, accuracy_shortlist, multivariate_accuracy_bonus, long_series_native
2. STDR (11.75)
   Robust seasonal-trend decomposition for noisier periodic signals.
   reasons: maturity:flagship, native_backed, channelwise_multivariate, accuracy_shortlist, long_series_native
3. STD (9.25)
   Fast seasonal-trend decomposition with dispersion-aware diagnostics.
   reasons: maturity:flagship, native_backed, channelwise_multivariate, long_series_native