Brummel
288e75e7fd
Ships the missing sum combinator(s) in aura-std so the north-star combine move
(C10) is expressible from shipped blocks. Two nodes: Add (parameterless two-input
f64 sum, companion to Sub) and LinComb { weights } (N-input weighted sum, weights
as tunable params + arity, C8/C12). Both withhold output until all inputs are
present (no implicit cold-leg 0.0).
Resolves the cycle-0007 fieldtest [friction]: the consumer had to hand-author a
project-local Add2 to combine two signals.
refs #11