chore: rename H7CAD to Open CAD Studio

Joining the OpenAEC Foundation (open-aec.com). Crate/struct become
OpenCADStudio, user-facing strings use the spaced "Open CAD Studio"
form, repo URLs point to HakanSeven12/open-cad-studio. Logo (window
icon + assets/logo.svg) redrawn with OCS initials. Drop examples/
binaries — unused.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/scene/grip.rs

@@ -1,4 +1,4 @@
-//! H7CAD-style grip editing.
+//! OpenCADStudio-style grip editing.
 
 use acadrust::Handle;
 use glam::{Mat4, Vec3};
@@ -13,7 +13,7 @@ pub const GRIP_HALF_PX: f32 = 5.0;
 
 // ── Active drag state ─────────────────────────────────────────────────────
 
-/// Stored on `H7CAD` while a grip is being dragged.
+/// Stored on `OpenCADStudio` while a grip is being dragged.
 #[derive(Clone, Debug)]
 pub struct GripEdit {
     /// Handle of the entity being edited.