Infinite alphabetic suffix sequence. n=0 yields the first suffix
past Decillion. The sequence is grouped into phases; phase L≥0
produces all (L+2)-letter strings, first all-lowercase, then
capital-first. Each phase has 2 × 26^(L+2) entries.
Format a Mag (log-magnitude) the same way big formats an f64,
but without an upper bound on representable values. Cuques, FPS,
and costs all flow through here once they live in Mag form.
Render a multiplicative magnitude (e.g. a MulFactor/EffectMul value)
with enough decimal places to show ~3 significant figures of its
distance from 1.0. Lets per-tree-node values like 1.00004 actually
read as ×1.00004 in the info pane instead of getting rounded to the
uninformative ×1.00.
Like mul_magnitude, but for an AddPercent magnitude (raw f64
where 0.01 == 1%). Picks decimal precision so the user can see
sub-percent values like +0.005% that would otherwise round to
+0.0%.