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.

crates/kernel/Cargo.toml

@@ -11,6 +11,7 @@ workspace = true
 [dependencies]
 solidcraft-geom = { workspace = true }
 serde = { workspace = true }
+serde_json = { workspace = true }
 thiserror = { workspace = true }
 log = { workspace = true }
 truck-modeling = { workspace = true }