Collapse the three verbatim-duplicated SMA-cross harness test fixtures
(synthetic_prices, sma_cross, composite_sma_cross_harness) in aura-engine's
blueprint.rs and sweep.rs #[cfg(test)] modules into one shared crate-root
#[cfg(test)] mod test_fixtures. Behaviour-preserving, test-only.
Auto-signed under /boss: all objective gates green (precondition, self-review,
grounding-check PASS) and a unanimous five-lens spec-skeptic panel returned
SOUND.
refs #53
Brummel
47179ce5a4