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/app/properties.rs

@@ -1,11 +1,11 @@
 use super::helpers::{entity_type_key, entity_type_label, title_case_word};
-use super::{H7CAD, VARIES_LABEL};
+use super::{OpenCADStudio, VARIES_LABEL};
 use crate::linetypes;
 use crate::scene::dispatch;
 use crate::ui;
 use acadrust::{EntityType, Handle};
 
-impl H7CAD {
+impl OpenCADStudio {
     /// Rebuild the PropertiesPanel from the current entity selection.
     /// Preserves UI state (open pickers, edit buffer) across refreshes.
     pub(super) fn refresh_properties(&mut self) {