release: prepare 0.1.5 with RDNA2 kernels and in-game DLSS/FSR switching

- Add native preset K kernels for gfx1030–gfx1036 using software matrix
  products, with fast and accuracy builds and RDNA2 motion kernels.
- Follow OptiScaler's DLSS and RR preset overrides, sanitize unsupported
  values and select the preset matching the feature's quality mode.
- Enable FSR 4 under NVIDIA GPU spoofing by exposing real AMD PCI IDs
  to OptiScaler and FidelityFX modules; bundle AMD's loader and upscaler.
- Keep K on native kernels in engine auto mode unless HIP is selected,
  and fall back to CUDA for M/L when shader_float8 is unavailable.
- Add native-engine K GPU timings, preset recreation harness controls
  and regression coverage; fix the input-wait test's glibc name clash.
- Update configuration, installer guidance and release documentation,
  simplify the README and move gameplay videos to docs/videos.md.

RDNA2 kernels remain untested on RDNA2 hardware; software matrix
arithmetic was validated against WMMA on RDNA3.

tests/test_input_wait.py

@@ -125,13 +125,13 @@ struct Feature {
 uint32_t words[4] = {0, 3, 4, 5}, markers[4] = {6, 3, 4, 5};
 Feature* current;
 int drains = 0, drainResult = 0;
-int sync() {
+int drain_sync() { // not sync(): glibc's <unistd.h> declares void sync()
     ++drains;
     assert(words[2] == 7); // drain may only run after the CPU released the blocked queue
     assert(current->ngxWaitActive); // ticket and input ownership survive the drain
     return drainResult;
 }
-struct { struct { int(*ctxSynchronize)() = sync; void(*timelineCancel)(void*) = nullptr; } cu; } g;
+struct { struct { int(*ctxSynchronize)() = drain_sync; void(*timelineCancel)(void*) = nullptr; } cu; } g;
 ''' + release + '\n' + complete + r'''
 int main() {
     Feature f; f.ngxInputSync.mapped = words; current = &f;