mix backtest --feature NaiveGradient now resolves to the same function
as --feature naive_gradient. Names are normalized via Macro.underscore,
so any casing works. Also prints the available functions when an
unknown feature is requested so typos don't produce an opaque
UndefinedFunctionError deep in the Enum.map stack.
Add Microwaveprop.Backtest: a feature-evaluation framework that runs
a (lat, lon, valid_time) -> float function over the historical QSO
corpus and a matched random-time baseline, reporting distribution
statistics, distance-binned lift, and band-stratified lift.
Adds four baseline feature wrappers around the current scorer inputs
(naive_gradient, td_depression, time_of_day, pressure), a mix backtest
CLI, and the first set of baseline reports under priv/backtest_reports
so downstream phases have a frozen reference point to compare against.
