Measure tool (I): pick one or two vertices, edges or faces for length/area/position, minimum distance with ΔX/ΔY/ΔZ and a line in the view, and the angle between planar faces or straight edges (MeasureCommand items, engine test); theme switch from the control channel no longer leaves stale scene colours

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

crates/engine/src/cmd/mod.rs

@@ -9,6 +9,8 @@ mod features;
 pub use features::auto_operation;
 mod file;
 mod inspect;
+mod measure_sel;
+pub(crate) use measure_sel::measure_items;
 mod sketch;
 mod sketch_constraints;
 mod sketch_create;