PR #228 exact-head testing build (5270e8d)

Exact-head testing build for PR #228 at commit 5270e8d649b713804a5587e75f083070393acebd.

This replaces the earlier bc9214d preview after a metadata-only commit amend. The source tree is identical, but these binaries were rebuilt by GitHub Actions from the current PR head.

Included changes:

• stable REQUIRED > VISIBLE > PREWARM priority for hybrid shader and pipeline work;
• PFIFO completion wakeups and timed owner-side retry service;
• bounded, paced prewarm with a conservative default window of one;
• owned-GLSL reuse plus distinct byte-limit and temporary queue-full handling;
• targeted result adoption and retained completed artifacts;
• synchronous pipeline-create timing in the existing cost field.

Artifacts:

• Windows x86_64 release ZIP containing the exact CI-built xemu.exe and license;
• Linux x86_64 release AppImage from the same exact-head CI run;
• basename-only SHA-256 manifest.

The Windows executable is archive-compressed rather than modified with an executable packer, preserving the exact CI-tested binary. Synthetic tests, traces, screenshots, and other evidence are intentionally not included.

Status: prerelease for manual validation. Exact-head CI and focused normal/sanitizer suites pass; controlled Windows synthetic testing confirms substantially fewer synchronous pipeline creations without claiming a general FPS increase.

Morrowind correction: the reported 12–14 FPS behavior also affected older builds and was traced to the persisted Hard FPU emulation setting being disabled during unrelated testing. Restoring it restored expected performance. That result was not caused by this shader patch. Repeatable automated Morrowind snapshot infrastructure remains tracked separately in Xemu-Test-Runner #61.