fix: default distributions to automatic GPU support with CPU fallback

docs/ROADMAP.md

@@ -49,6 +49,10 @@ Status: implementation started; no production release yet. Windows VM tests use
 - [ ] Isolated extraction workers with timeouts and resource ceilings.
 
 ## 5. Release gates
+- [x] Normal worker build/staging defaults to hardware-detecting auto with CPU
+  fallback; missing Vulkan/glslc fails configuration rather than hiding GPU loss.
+- [ ] Provision release-build GPU SDKs and verify one hardware-detecting package
+  per OS/architecture, including missing-driver fallback and dependency closure.
 - [x] Windows desktop archive packager includes explicit runtime/helper files
   and notices, checks architecture and records per-file checksums; excludes
   model caches and user data. Controlled packaging regression tests pass.