Add accuracy mode and GLIBC 2.41 release builds

Add default-off PreferAccuracy with conservative native variants for every RDNA3/RDNA4 target and a separate JIT cache. Preserve fast defaults and reject mixed accuracy sets.

Add a pinned Debian build environment, rebuild all release components against GLIBC 2.41, and include toolchain provenance and release notes for the accuracy changes and the preceding artifact/synchronization fixes. Refs #6; CPU-overhead confirmation for #7 remains pending.

kernels/m/swin_common.h

@@ -9,6 +9,9 @@
 #include <hip/hip_runtime.h>
 #include <stdint.h>
 #include "../common/wmma_layout.h"
+#ifdef D4R_ACCURACY
+#define SWIN_EXACT
+#endif
 #if defined(D4R_FP8_WMMA) && D4R_WMMA_LAYOUT != 12 && defined(__AMDGCN__)
 #error "D4R_FP8_WMMA needs the gfx12 WMMA layout"
 #endif