zluda: coalesce pair shadow stores, signed native FP8 conversion

Patch 0011 merges a complete accumulator-register pair overwrite into one
shadow-layout conversion (reads, rewritten shadow accesses and block
boundaries prevent it; partial writes keep read/modify/write), and requests
eight waves per SIMD for gfx12 native-FP8 functions. Patch 0012 keeps signs
in the native conversion: finite overflow clamped, NaNs mapped to signed
infinity, post-conversion sign masks gone; plain and ReLU remain
exhaustive-table identical to the software codec.

Eighty-frame harness at 720p->4K, excluding the first twenty: control
24.764 ms, coalescing 23.340 ms, plus eight waves 20.135 ms, plus signed
conversion 16.234 ms (15.144 ms with the harness idle gap removed); all
eighty saved frames byte-identical to the matching control. Twelve- and
ten-wave budgets regress (25.56/24.61 ms); fast math changes the image
(18.92 ms) and is not selected.

scripts/build_release_glibc241.sh

@@ -5,7 +5,7 @@
 set -euo pipefail
 ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
 : "${D4R_RELEASE_BUILD_ROOT:?set the build output directory}"
-: "${D4R_ZLUDA_SRC:?set a build-local ZLUDA checkout with patches 0002-0008 applied}"
+: "${D4R_ZLUDA_SRC:?set a build-local ZLUDA checkout with patches 0002-0012 applied}"
 : "${D4R_VKD3D_SRC:?set a build-local vkd3d-proton checkout with patches 0001-0003 applied}"
 : "${D4R_ROCM_DIR:?set ROCm with clang and device libraries}"
 BUILD="$(realpath -m "$D4R_RELEASE_BUILD_ROOT")"