fix: gui CI after closure lifetime merge

[GGRei]

Summary

This updates the v-gui CI after the closure lifetime/reclaim work landed in V.

The Windows job was still using an outdated V compiler path, which could miss the new closure lifetime/reclaim API used by v-gui. This PR makes the Windows job resolve and build/cache the current V compiler revision, so it stays aligned with upstream V.

It also refreshes the Windows dependency cache keys from the resolved V/vglyph revisions, so compiler or dependency updates do not keep reusing stale caches.

Finally, it reduces CI noise and runtime by avoiding warning-fatal full example sweeps and duplicate full example rebuilds on push runs.

Changes

• Resolve the current V compiler revision in Windows CI.
• Cache the Windows V compiler by exact V revision.
• Refresh Windows vcpkg and vglyph cache keys from the resolved V/vglyph revisions.
• Keep changed-example -W checks on pull requests.
• Avoid full example v -check sweeps for .v examples, since those currently fail on transitive gui/vglyph diagnostics rather than example-local syntax.
• Run full example compilation on push only once, using non warning-fatal mode.
• Format examples/showcase.v so the CI format check passes.

Notes

This PR does not change the closure lifetime/reclaim behavior itself.

The .v examples are still covered by compilation checks. The removed/relaxed parts were CI warning-fatal or duplicate paths that were causing false failures or unnecessary rebuild time.

Tests

v fmt -verify examples/showcase.v
v -check examples/_check.vsh
git diff --check