Feature walks: generate them from field roles with #[derive(Walk)] (#1251)

The three walks over a feature (expressions, references, geometry) are generated from FeatureKind by #[derive(Walk)] in a new proc-macro crate, solidcraft-derive, from #[walk(...)] attributes written next to each field. The hand-written walks in params.rs, feature_refs.rs and feature_geometry.rs are gone; Ruled Surface and Extend have their attributes, and the three golden walk records are unchanged.

Co-authored-by: jijinbei <[email protected]>

Cargo.toml

@@ -24,10 +24,15 @@ solidcraft-io = { path = "crates/io" }
 solidcraft-engine = { path = "crates/engine" }
 solidcraft-ui-egui = { path = "crates/ui-egui" }
 solidcraft-mcp = { path = "crates/mcp" }
+solidcraft-derive = { path = "crates/derive" }
 
 # foundation
 thiserror = "2"
 serde = { version = "1", features = ["derive", "rc"] }
+# derive macros (crates/derive); already in the tree through serde_derive
+proc-macro2 = "1"
+quote = "1"
+syn = { version = "2", features = ["full"] }
 serde_json = { version = "1", features = ["float_roundtrip"] }
 log = "0.4"
 sha2 = "0.10"