shim: adaptive marker polling, opt-in GPU-side input wait/completion and RGBA8 output

- [Interop] MarkerPollUs = auto is the new default: the input-marker wait learns when
  each feature's inputs become ready, sleeps in <=200 us chunks, yields near the
  prediction and backs off when late (d4r_input_wait.h); a number keeps fixed pacing
  (0 yields). d4r_config.py no longer exports 200 when the key is unset

- D4R_SHIM_GPU_INPUT_WAIT=1 (experimental, split VRAM, age 0): NGX's null stream
  waits on a coherent Vulkan word imported into HIP (d4rStreamWaitValue32Eq) instead
  of CPU polling. The original readback marker stays the authority; a CPU watchdog
  releases discarded lists and timeouts. Denoiser, verify, capture and dilation
  frames keep the CPU wait

- D4R_SHIM_GPU_COMPLETION=1 (needs GPU_INPUT_WAIT): the bridge writes a completion
  word right after the native output kernel (d4rNgxWriteValue32), and the game's queue
  polls it with a bounded compute wait (kernels/support/vulkan_wait.comp), replacing
  the split list's CPU timeline signal. frame_retired writes the same word on every
  failure path

- D4R_SHIM_NATIVE_COMPLETION=1: a null-stream callback in the bridge signals the
  split timeline (d4rNgxTimeline*); D4rFrameCompletion::can_signal only releases the
  oldest outstanding frame

- RGBA8 output: tex_common.h adds an 'R4' redirect tag, so K's native output kernel
  stores packed RGBA8 directly (D4R_SHIM_OUTPUT_RGBA8=1, checked against the kernel
  manifest by d4rOutputKernelRgba8). Host packing handles RGBA8 too.
  patches/vkd3d-proton/0004 (VKD3D_D4R_LINEAR_RGBA8=WxH) makes such outputs linear and
  exportable so the result can be written in place

- D4R_SHIM_FUSE_RGBA8_INPUT=1: one Vulkan pass converts and copies RGBA8 color input
  (vulkan_read.comp mode 5 matches the blit's toward-zero halves, plus a row stride)

- profiling: thread CPU time from the Unix bridge (Wine's GetThreadTimes ticks at
  10 ms); game-queue D3D12 timestamps (vk_input/vk_dlss_wait/vk_output/vk_total);
  gpu_eval split into input_gpu_wait and dlss_gpu; D4R_PROFILE_GPU_EVENTS,
  _TIMESTAMPS, _LOG and _CPU_TIME=0 switch off individual parts for bisection

- bridge: D4R_NGX_STREAM_PRIORITY=high|normal runs NGX on a priority stream
  (off by default; no gain measured)

- release_feature: a feature already marked retiring by a failed drain can still
  be released normally

- harness: RGBA8 with motion and jitter scenes (re-quantized each frame),
  D4R_HARNESS_RGBA8_RAMP, D4R_HARNESS_THRASH_MB to evict L2/Infinity Cache before
  each evaluation

- kernels/native: in_hoist.py and split_output_paths.py (opt-in scheduling
  experiments); scripts/build_k_ldr_output.sh builds K's LDR output with an
  optional D4R_LDR_OUTPUT_MAX_VGPR cap

- tests: test_input_wait.py and test_latency_optimizations.py; MarkerPollUs and
  frame-completion tests updated

kernels/support/vulkan_read.comp

@@ -2,7 +2,7 @@
 layout(local_size_x=8, local_size_y=8) in;
 layout(set=0, binding=0) uniform sampler2D sourceImage;
 layout(std430, set=0, binding=1) writeonly buffer Pixels { uint pixels[]; };
-layout(push_constant) uniform Size { uint width; uint height; uint mode; } size;
+layout(push_constant) uniform Size { uint width; uint height; uint mode; uint stride; } size;
 // Match the CPU canonical conversion, including round-to-even and subnormals.
 uint halfBits(float value) {
     uint bits = floatBitsToUint(value);
@@ -26,14 +26,24 @@ uint halfBits(float value) {
     if (remainder > halfway || (remainder == halfway && (m & 1u) != 0u)) ++result;
     return result;
 }
+// Mode 5 is only for RGBA8 UNORM: values are zero or normal positive halves. Preserve
+// the blit's toward-zero conversion; other modes keep the canonical round-to-even path.
+uint halfRtz(float value) {
+    uint b = floatBitsToUint(value);
+    if (value == 0.0) return 0u;
+    return (((b >> 23) - 112u) << 10) | ((b & 0x7fffffu) >> 13);
+}
 void main() {
     uvec2 p = gl_GlobalInvocationID.xy;
     if (p.x >= size.width || p.y >= size.height) return;
     ivec2 extent = textureSize(sourceImage, 0);
-    uint index = p.y * size.width + p.x;
+    uint index = p.y * size.stride + p.x;
     vec4 value = all(lessThan(ivec2(p), extent))
         ? texelFetch(sourceImage, ivec2(p), 0) : vec4(0.0);
-    if (size.mode == 1u) { // canonical RGBA16F color
+    if (size.mode == 5u) {
+        pixels[index * 2u] = halfRtz(value.x) | (halfRtz(value.y) << 16);
+        pixels[index * 2u + 1u] = halfRtz(value.z) | (halfRtz(value.w) << 16);
+    } else if (size.mode == 1u) { // canonical RGBA16F color
         pixels[index * 2u] = halfBits(value.x) | (halfBits(value.y) << 16);
         pixels[index * 2u + 1u] = halfBits(value.z) | (halfBits(value.w) << 16);
     } else if (size.mode == 3u) { // canonical RG16F motion