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/io/obj.rs

@@ -27,7 +27,7 @@ pub fn parse_obj(src: &str, color: [f32; 4]) -> Option<MeshModel> {
             "v" => {
                 let vals: Vec<f32> = parts.filter_map(|s| s.parse().ok()).collect();
                 if vals.len() >= 3 {
-                    // OBJ: Y-up right-handed.  H7CAD viewport is also Y-up → keep as-is.
+                    // OBJ: Y-up right-handed.  OpenCADStudio viewport is also Y-up → keep as-is.
                     positions.push([vals[0], vals[1], vals[2]]);
                 }
             }

src/io/pdf_export.rs

@@ -78,7 +78,7 @@ fn build_pdf(
     rotation_deg: i32,
     plot_style: Option<&PlotStyleTable>,
 ) -> Vec<u8> {
-    let mut doc = PdfDocument::new("H7CAD Export");
+    let mut doc = PdfDocument::new("Open CAD Studio Export");
     let mut ops: Vec<Op> = Vec::new();
 
     // White page background.

src/io/print_to_printer.rs

@@ -28,7 +28,7 @@ pub async fn print_wires(
     plot_style: Option<PlotStyleTable>,
 ) -> Result<String, String> {
     // ── 1. Write to a named temp file ─────────────────────────────────────
-    let tmp_path = std::env::temp_dir().join("h7cad_print.pdf");
+    let tmp_path = std::env::temp_dir().join("open_cad_studio_print.pdf");
     pdf_export::export_pdf(
         &wires,
         &hatches,

src/io/step.rs

@@ -199,7 +199,7 @@ pub fn build_step(meshes: &[&MeshModel]) -> Option<String> {
     let msb_id = alloc();
     writeln!(
         data,
-        "#{} = MANIFOLD_SOLID_BREP('H7CAD_Solid',#{});",
+        "#{} = MANIFOLD_SOLID_BREP('OpenCADStudio_Solid',#{});",
         msb_id, shell_id
     )
     .ok();
@@ -217,7 +217,7 @@ pub fn build_step(meshes: &[&MeshModel]) -> Option<String> {
     writeln!(data, "#{} = GEOMETRIC_REPRESENTATION_CONTEXT(3);", gc_id).ok();
     writeln!(
         data,
-        "#{sr_id} = SHAPE_REPRESENTATION('H7CAD_Shape',(#{}),#{gc_id});",
+        "#{sr_id} = SHAPE_REPRESENTATION('OpenCADStudio_Shape',(#{}),#{gc_id});",
         msb_id
     )
     .ok();
@@ -227,7 +227,7 @@ pub fn build_step(meshes: &[&MeshModel]) -> Option<String> {
     let file = format!(
         "ISO-10303-21;\n\
          HEADER;\n\
-         FILE_DESCRIPTION(('H7CAD STEP export'),'2;1');\n\
+         FILE_DESCRIPTION(('Open CAD Studio STEP export'),'2;1');\n\
          FILE_NAME('{ts}','','',(''),'',' ',' ');\n\
          FILE_SCHEMA(('CONFIG_CONTROL_DESIGN'));\n\
          ENDSEC;\n\

src/io/stl.rs

@@ -67,7 +67,7 @@ pub fn build_stl(meshes: &[&MeshModel]) -> Option<Vec<u8>> {
 
     // 80-byte header.
     let mut header = [0u8; 80];
-    let title = b"H7CAD STL export";
+    let title = b"Open CAD Studio STL export";
     header[..title.len()].copy_from_slice(title);
     buf.extend_from_slice(&header);