Render: integrated workspace, preview image jobs and opaque PBR (#1046)

Lands the Render workspace (R3), bounded preview-image jobs with cancellation and atomic PNG export (R4a), and opaque PBR looks as one change.

- Render workspace: an overlay-free product preview on the installed GPU device. Returning to Design restores its camera. render.scene and render.settings.apply are added.
- Image jobs: render.preflight/start/status/cancel/export run bounded CPU preview jobs. Export captures the job, overwrite choice and document, and checks the caller's file scope before writing.
- Opaque PBR: looks can carry metal fraction, roughness and dielectric IOR. The product viewport and preview PNG use them; geometry and mass are unchanged. The v1 catalog export refuses PBR rather than dropping it.
- Render setups and PBR looks are saved under design format 21. Labels are in en/de/ja/ko/zh/ru.

Supersedes #706 and #800. Refs #620, #673, #756, #1004.

Contributed by @0xlillith.

Co-authored-by: lillith <35337584+0xlillith@users.noreply.github.com>

crates/ui-egui/src/documents.rs

@@ -27,6 +27,7 @@ pub struct DocSlot {
 /// The per-design part of the UI state (what is hidden, shown or locked).
 #[derive(Clone, Debug, Default)]
 struct DocView {
+    render: crate::render_workspace::ViewState,
     sketch_choices: crate::sketch_families::Choices,
     hidden_profiles: Vec<u64>,
     shown_dims: Vec<u64>,
@@ -64,6 +65,7 @@ impl Documents {
 fn take_view(app: &mut SolveApp) -> DocView {
     let u = &mut app.ui;
     DocView {
+        render: std::mem::take(&mut app.render_workspace.view),
         sketch_choices: std::mem::take(&mut app.sketch_choices),
         hidden_profiles: std::mem::take(&mut u.hidden_profiles),
         shown_dims: std::mem::take(&mut u.shown_dims),
@@ -72,6 +74,9 @@ fn take_view(app: &mut SolveApp) -> DocView {
 }
 
 fn put_view(app: &mut SolveApp, v: DocView) {
+    app.render_workspace.view = v.render;
+    crate::render_workspace::invalidate_scene(app);
+    crate::render_workspace::sync_backend(app);
     app.sketch_choices = v.sketch_choices;
     let u = &mut app.ui;
     u.hidden_profiles = v.hidden_profiles;
@@ -81,6 +86,9 @@ fn put_view(app: &mut SolveApp, v: DocView) {
 
 /// Put `slot` into the app and return what was there.
 fn swap_in(app: &mut SolveApp, slot: DocSlot) -> DocSlot {
+    if crate::render_workspace::active(app) {
+        let _ = crate::render_workspace::enter(app, false);
+    }
     // Whatever was going on in the design leaves with it.
     crate::sketch_text_move::cancel_drag(app);
     crate::dialogs::cancel(app);
@@ -162,6 +170,7 @@ pub fn adopt(app: &mut SolveApp, session: Session) {
         app.menu.props = None;
         crate::sketch_attachment_ui::clear(app);
         app.session.replace_design(session);
+        crate::render_workspace::reset_document(app);
         app.sketch_choices = crate::sketch_families::Choices::default();
         app.session.invalidate_view(rev);
         app.cam = Camera::default();