Define a kernel-neutral native B-rep format and guarded adapter (#461)

A SolidCraft-owned portable B-rep schema (geometry schema 2 with analytic curves and surfaces, explicit frames and ranges, fitted intersection curves) and a versioned body envelope (SCBREP03) with its own metadata records, a bounded binary codec, a validator with resource budgets, and an adapter that refuses what it can't convert exactly. Pinned by a box-and-fillet golden fixture. Not yet written by application saves. Refs #303.

Cargo.lock

@@ -3375,6 +3375,7 @@ version = "0.7.0"
 dependencies = [
  "log",
  "serde",
+ "serde_json",
  "solidcraft-geom",
  "thiserror 2.0.21",
  "truck-meshalgo",