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/ui/update_notice.rs

@@ -140,7 +140,7 @@ pub fn view_window<'a>(latest: &'a str, body: &'a str) -> Element<'a, Message> {
     let header = container(
         column![
             text("New Release Available").size(20).color(ACCENT),
-            text("A newer H7CAD version is published on GitHub.")
+            text("A newer Open CAD Studio version is published on GitHub.")
                 .size(11)
                 .color(DIM),
         ]