d8c6938027
C29 compile/unit seam, tasks 4+5 of the self-description plan. aura-engine (task 4): derive_signature stamps doc: "" with the stance recorded in-code -- a derived composite signature is graph wiring, not a vocabulary entry; no seam walks its doc, the described surface is the composite's own doc at the register seam. All in-crate test literals thread doc: "test-only schema". Domain crates (task 5): the 12 production builder sites in aura-market / aura-strategy / aura-backtest carry authored meaning lines; test sites in aura-backtest / aura-composites / aura-ingest thread the test-only doc. Three texts were corrected against the actual node semantics after quality review rather than kept from the first authoring pass: SimBroker is the frictionless integrator of held exposure times price return into cumulative pip equity (no fills/stops/lifecycle -- that is PositionManagement's domain), the shared cost-node line names the PM-geometry inputs and both charge modes (AtClose / PerHeldCycle) instead of a "per-trade gross R" mapping, and LongOnly's line conditions on its enabled param and speaks port-term "exposure". Gates: cargo test green for all six touched crates (engine, market, strategy, backtest, composites, ingest); the workspace-wide gate follows task 6 (aura-runner is the one remaining unthreaded site, E0063 by design until then). refs #316