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>

apps/solidcraft-cli/src/main.rs

@@ -24,6 +24,7 @@ mod crashes;
 mod fuzz;
 mod oracle;
 mod recipe;
+mod render;
 mod spatial;
 
 use std::process::ExitCode;
@@ -45,6 +46,7 @@ const USAGE: &str = "usage:
   solidcraft-cli bench-open <design.solidcraft | part.step> [--parse-only]
   solidcraft-cli bench-agent [--scale F] [--save design.solidcraft] [--script-out script.json]
   solidcraft-cli snapshot <script|design> --out shot.png [--width W] [--height H] [--view iso|front|back|top|bottom|left|right]
+  solidcraft-cli render <script|design> --out image.png [--setup NAME] [--width W] [--height H] [--transparent] [--overwrite] [--timeout SECONDS]
   solidcraft-cli exec <command> [json-params]
   solidcraft-cli commands
   solidcraft-cli recipe <recipe.json>
@@ -63,6 +65,7 @@ fn main() -> ExitCode {
         Some("eval" | "inspect") => cmd_eval(&args[1..]),
         Some("script") => cmd_script(&args[1..]),
         Some("snapshot") => cmd_snapshot(&args[1..]),
+        Some("render") => render::run(&args[1..]),
         Some("exec") => cmd_exec(&args[1..]),
         Some("commands") => {
             use std::io::Write as _;