Add the modelcraft-decks crate (empty: error type only) (#19)

So the Abaqus, Nastran and LS-DYNA writer tasks add their modules in parallel.


Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

Co-authored-by: jyviko <2501648+jyviko@users.noreply.github.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

Cargo.toml

@@ -15,6 +15,7 @@ repository = "https://github.com/jyviko/modelcraft"
 modelcraft-model = { path = "crates/model" }
 modelcraft-geometry = { path = "crates/geometry" }
 modelcraft-mesh = { path = "crates/mesh" }
+modelcraft-decks = { path = "crates/decks" }
 modelcraft-engine = { path = "crates/engine" }
 modelcraft-testkit = { path = "crates/testkit" }
 modelcraft-render = { path = "crates/render" }