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>

assets/locales/en.json

@@ -1046,5 +1046,59 @@
   "update.dmg_opened": "The disk image is open and verified: drag SolidCraft to Applications, replacing the old copy, then restart SolidCraft.",
   "update.install_failed": "The update didn't install: {error}. Nothing was changed; Download gets the package instead.",
   "cmd.render_settings_get": "Render Settings",
-  "cmd.render_settings_set": "Save Render Settings"
+  "cmd.render_settings_set": "Save Render Settings",
+  "cmd.render_scene": "Inspect Render Scene",
+  "cmd.render_settings_apply": "Apply Render Camera",
+  "toolbar.render": "RENDER",
+  "toolbar.render_scene": "SCENE",
+  "render.preview": "Integrated preview",
+  "render.preview_help": "Raster shading and blended transparency. Refraction, HDRI and final rendering are not available yet.",
+  "render.setup_name": "Setup name",
+  "render.background": "Scene background",
+  "render.perspective": "Perspective camera",
+  "render.fit": "Fit Product",
+  "render.restore_camera": "Restore Saved Camera",
+  "render.save_setup": "Save Setup",
+  "render.unsaved": "Unsaved preview changes",
+  "render.reload_settings": "Reload Saved Settings",
+  "render.unavailable_preview": "This setup requests an unavailable preview profile.",
+  "render.use_preview": "Use Integrated Preview",
+  "render.navigation_help": "Drag to orbit; middle-drag to pan; scroll to zoom. Save Setup records the current camera.",
+  "render.return_design": "Return to Design",
+  "render.image_title": "Render Image",
+  "render.image_help": "CPU preview image · PNG · approximate transparency",
+  "render.image_width": "Width",
+  "render.image_height": "Height",
+  "render.image_transparent": "Transparent background",
+  "render.image_check": "Check Render Request",
+  "render.image_supported": "Render request is supported; the queue and memory pool are checked again at start.",
+  "render.image_queued": "Waiting to render",
+  "render.image_preparing": "Preparing image",
+  "render.image_running": "Rendering image",
+  "render.image_encoding": "Encoding PNG",
+  "render.image_cancelling": "Cancelling",
+  "render.image_cancelled": "Render cancelled",
+  "render.image_completed": "Image ready to export",
+  "render.image_failed": "Render failed",
+  "render.image_unknown": "Render status unavailable",
+  "render.image_reduce": "Try a smaller image or simpler scene.",
+  "render.image_cancel": "Cancel Render",
+  "render.image_stale": "This image uses the scene captured before subsequent changes.",
+  "render.image_start": "Start Render",
+  "render.image_overwrite": "Replace existing file",
+  "render.image_export": "Export PNG",
+  "cmd.render_preflight": "Check Render Request",
+  "cmd.render_start": "Render Image",
+  "cmd.render_status": "Render Progress",
+  "cmd.render_cancel": "Cancel Render",
+  "cmd.render_export": "Export Render Image",
+  "toolbar.image": "IMAGE",
+  "appearance.surface_response": "Surface response",
+  "appearance.pbr_opaque": "Opaque PBR",
+  "appearance.metallic": "Metallic",
+  "appearance.roughness": "Roughness",
+  "appearance.dielectric_ior": "Dielectric IOR",
+  "appearance.pbr_help": "View this surface in Render or a product PNG. No refraction or transmission.",
+  "render.opaque_preview_help": "Opaque PBR and simple colors; blended transparency. Refraction, HDRI and final rendering are not available yet.",
+  "render.opaque_image_summary": "Preview PNG · opaque PBR · blended transparency"
 }