Parameters: unit-aware parameters (an inch parameter reads bare numbers as inches), atan2/mod/trunc and clearer unit errors, cycle paths (a → b → a), rename with every reference following (expressions, feature inputs, dimensions, favourites, comments), deletes refused with the list of users, parameter errors shown on the features using them, parameters.add/rename/delete/comment/users/graph/complete and expr.evaluate; ChangeParameterCommand renames and favourites; hostile test no longer writes stray files

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AS5Tn3xieewUSg3uxrMVdL

crates/engine/src/cmd/mod.rs

@@ -11,6 +11,7 @@ mod file;
 mod inspect;
 mod measure_sel;
 pub(crate) use measure_sel::measure_items;
+mod parameters;
 mod sketch;
 mod sketch_constraints;
 mod sketch_create;
@@ -121,6 +122,7 @@ pub fn command_specs() -> Vec<&'static CommandSpec> {
     v.extend(features::COMMANDS.iter());
     v.extend(component::COMMANDS.iter());
     v.extend(edit::COMMANDS.iter());
+    v.extend(parameters::COMMANDS.iter());
     v.extend(file::COMMANDS.iter());
     v.extend(inspect::COMMANDS.iter());
     v