StructuralEngineering 

Protocol Buffers bindings for the structuralengineering schema (generated from .proto at build time via Grpc.Tools).

Model primitives for the structuralengineering schema: preset Material instances for common structural steel grades (EN 10025-2), with Section and Units presets to follow.

Input-validation primitives for structuralengineering model messages (scaffolding in v0).

Design-check implementations (Eurocode 3 §6.2.3 tension member as the first) for the structuralengineering schema.

gRPC client stub for the structuralengineering solver service. Concrete transport lands in v0.2 (ADR 0004).