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/k/pwin_common.h

@@ -10,6 +10,9 @@
 #include <hip/hip_runtime.h>
 #include <stdint.h>
 #include "../common/wmma_layout.h"
+#if defined(D4R_ACCURACY) && defined(PWIN_F32ACC)
+#undef PWIN_F32ACC
+#endif
 #pragma clang fp contract(off)
 
 typedef _Float16 half_t;