C29 compile/unit seam, task 3 of the self-description plan: every
aura-std NodeSchema literal threads its one-line doc. Four texts were
corrected against the actual eval/finalize semantics rather than taken
from the plan table verbatim: Delay is a lag-N register (not one-step),
GatedRecorder flushes an ungated final row at finalize, Latch is a
level-sensitive set/reset register (captures no input), SeriesReducer
emits its single summary row at finalize (not per cycle).
Gate: cargo build -p aura-std --lib clean; full std test run follows at
the all-crates gate once strategy/backtest/engine thread their sites
(the earlier per-crate test gate was unsatisfiable in isolation --
std's dev-deps pull crates whose sites belong to later tasks).
refs #316
First half of the #281 clock-enable set: Sign promotes the private
sign0() semantics to vocabulary (strict comparisons; NaN and -0.0
fall to 0.0), Select is the stateless 2:1 mux that consumes Bool
back into the F64 plane. Both zero-arg, Firing::Any, rostered
(count pins 29→31); an engine E2E drives both through the real
GraphBuilder→compile→run seam.
refs #281