fix: default distributions to automatic GPU support with CPU fallback

docs/VALIDATION.md

@@ -11,8 +11,15 @@ The Windows archive packager has two controlled Python regressions: complete
 required file collection with checksum verification and user-settings exclusion,
 and mismatched worker architecture preserving the previous archive. Both pass.
 An actual CPU-only Tauri embedded-frontend Release build has been started;
-archive creation, native launch outside the source tree and clean-machine
-installation remain unverified until its completion and separate checks.
+the embedded-frontend Release application build completed in 7m 25s. CPU-only
+describes its VM test context, not a supported end-user edition. The normal
+worker build/staging defaults are now auto and require GPU compilation support
+alongside CPU fallback. The previously staged CPU worker remains an internal
+test artifact; archive creation, automatic-runtime dependency packaging, native
+launch outside the source tree and clean-machine installation remain unverified.
+Actual `auto` configuration correctly rejected this VM's missing Vulkan library,
+headers and `glslc`; no GPU-capable worker/package is claimed. Both staging
+regressions still pass using explicit internal CPU test configuration.
 
 Offline staging now verifies the native license and every bundled Google asset
 before modifying resources. Two Python regressions verify missing-model rejection