engine/rr: native preset F (DLSS 4.5 Ray Reconstruction) and the reference's fused roundings

- engine/compile_rr2.py, runtime_rr2.inc, engine/rr/rr2_m.comp, exposure_f.comp,
  gen_rr2_enc0.py, rr2_pack.py, rr2_ref.py: the rr2_* model (nvngx_dlssd.dll 310.9's
  third network) as d4r's own shaders - exposure, enc0 gather/block split, enc1-5 and
  dec4-0 through one matrix shader, translated output passes; weights packed from the
  DLL, argument blocks from the capture
- ptx2rr: match the driver's fused roundings - opaque-zero OR around cvt.rn.f16.f32
  against v_fma_mix, half-away-from-zero formatted stores, UNORM 10:10:10:2 as RGBA32F
  of q/1023, OCML tanhF with the AMDGPU exp lowering, binary16 fma and fetch roundings;
  --probe for register bisection against ZLUDA
- dec0_m/swin_m/enc0_*: RR_MIX build option (D4R_RR_MIX=1), one v_fma_mix rounding per
  32-deep step, ~5% faster, not bit-exact; default build stays exact
- runtime_rr.inc: RModel/REngine dispatch to the D4RR0002 model; replay_rr: RGBA32F and
  A2B10G10R1010 texel sizes, roughnessPacked bit, larger debug staging
- shim: engine\rr-f model slot, 310.9 version probe so preset F is only claimed when the
  CUDA path has it; d4r.ini / d4r_config.py Model = F; run_rr_engine_compare.sh D4R_RR_DLL
- kernels/rr/swin_native.h + rr_swin_native_test.cpp: HIP port of encoder 1 for the
  FP8-product and rounding cost measurements
- engine/rr/README: preset F's block, options, capture-by-capture results, timings and
  the open camera-matrix difference

engine/rr/build_native_model.sh

@@ -42,6 +42,8 @@ PRESET="$(awk '$1 == "preset" { print $2 }' "$OUT/rr.txt")"
 DEFS=(-DRR_EXACT_CONVERT); [[ "$PRESET" == 4 ]] && DEFS+=(-DRR_PRESET_D)
 # D4R_RR_RELAXED=1: one rounding where NVIDIA has two (engine/rr/rr_exact.glsl): faster, not bit-exact
 [[ -n "${D4R_RR_RELAXED:-}" ]] && DEFS+=("-DRR_RELAXED=$D4R_RR_RELAXED")
+# D4R_RR_MIX=1: the 32-deep steps round once through v_fma_mix (the shaders' K32): ~5% faster, not provably bit-exact
+[[ "${D4R_RR_MIX:-0}" == 1 ]] && DEFS+=(-DRR_MIX)
 glsl() { # glsl OUT.spv SOURCE INCLUDE_DIR...
     local out="$1" src="$2"; shift 2
     local dir inc=(); for dir in "$@"; do inc+=("-I$dir"); done