forked from 1b-agent/opencadstudio-upstream
Adds ui_selection_overlay bench (benches/performance_benchmarks.rs + README metric 31): builds a representative selection overlay element (snap, crosshair, UCS tripod, 128 grips quick / 4096 capped full) and times widget-tree construction. Measured 0.4us typical, 2.4us at the cap (threshold 50us). Adds ribbon/statusbar section marks to the chrome bucket in view_main (src/app/view/mod.rs) so live PERF=1 view-detail traces attribute those two costs separately. Gated on the existing perf switch; no-op otherwise. Adds pub re-exports of CursorType/IsoPlane (src/app/mod.rs) for the bench fixture (same pattern as the existing grip re-exports). Ranked result over all ui_* benches: ribbon view construction ~556us (largest; follow-up already tracked), everything else under 50us or synthetic-fixture shapes. No new follow-up filed. GPU and canvas-draw costs are unmeasurable in headless runs (view() never executes there).