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>

docs/book/src/dev/local-libraries.md

@@ -24,6 +24,14 @@ unless **Replace existing library file** is explicitly selected. Export is a sna
 the design definitions, not an automatic merge with entries in an existing catalog.
 Editing a copied look/material uses the normal commands and does not edit its source.
 
+The combined render integration uses main's merged #1127 asynchronous picker.
+Model edits and tab changes wait for its answer while drawing/resizing continues.
+Overwrite consent is captured before opening; export snapshots the design when
+`library.export` runs after choosing the destination. Document identity is checked,
+and an old library answer cannot replace another Appearance editor. Cancellation
+does not read or write a library. The earlier #1114 candidate is no longer a runtime
+dependency of the refreshed consumer.
+
 The desktop panel applies appearances. Physical-material import/assignment is available
 through `library.apply`; imported definitions also appear in the existing material list.
 The browser can export a library through the existing download service. Interactive local
@@ -123,3 +131,8 @@ The copied design remains independent after successful assignment, undo/redo and
 reopening. This library has no dependency on the pending render stack and does not change
 the document format. User-visible evidence and actual native/wasm results are recorded in the PR;
 geometry/robustness checks remain separate and no reference baseline is weakened.
+
+The opaque PBR consumer makes v1 export fail explicitly when any body, component,
+face or material-default appearance contains PBR parameters. Neither overwrite consent
+nor an existing output file permits a lossy downgrade; use the richer transport
+when available. Scalar catalog imports still select the scalar response explicitly.