Change CadModule::ribbon_groups() from -> Vec<RibbonGroup> to -> &[RibbonGroup],
backed by a per-module OnceLock cache. The ribbon group tree is static data
(&'static str, Copy enums) that was being fully reconstructed — Vecs, String
clones, enum discriminants — on every call, including all three per-frame
call sites (view(), dropdown_overlay(), style_combo_overlay()).
- 7 built-in modules + 2 plugin templates cache via function-local OnceLock.
Safe because each is a unit struct with exactly one instance per process
(plugins run in isolated child processes; see PluginProcess::spawn()).
- SharedCadModule avoids the static pattern entirely, storing groups in an
instance field (owned.rs).
- IPC runner converts &RibbonGroup -> OwnedRibbonGroup directly via new
From<&T> impls, avoiding an intermediate clone.
- render_small/render_large and the two make_tool_row closures now borrow
(&RibbonItem, &[ToolDef]) instead of taking ownership, so the view loop
doesn't need to clone items to satisfy the old by-value signatures.
- Various match-ergonomics deref fixes (*id, *default, *icon, etc.) from
the &RibbonItem pattern change.
