feat(render3d): HDR10 output, and DLSS that stays still

HDR output: an HDR10 swapchain (A2B10G10R10, ST 2084 over BT.2020) when the
setting asks and the display offers it, with HDR metadata. The tonemap's HDR10
variant keeps the SDR picture up to a 200-nit paper white and rolls highlights
on to 1000 nits; the overlay's converts the interface to the same white. The
screen and LDR images go 10-bit with it; screenshots refuse while it is on.
OpenGL and the Vulkan SDR frame are unchanged. The instance asks for
VK_EXT_swapchain_colorspace. HDR metadata only where the loader has
vkSetHdrMetadataEXT: Streamline's interposer does not, and calling the thunk
crashed the game the moment the swapchain came up HDR10. PC 4K monitor: HDR10,
validation 0. R3D_HDR overrides the setting.

DLSS:
- the vertical jitter offset flips with Streamline's image (rows from the top):
  unflipped, Quality resolved the ground into concentric rings;
- preset K in every mode: the default M put Performance at 18 ms a frame at 4K
  on an RTX 3070 Ti (33 fps against 41 with DLSS off; with K, 60);
- the camera is jittered only while this frame holds a token and the last
  evaluate worked.
R3D_DLSS_PRESET, R3D_CAM_LOG (the camera and DLSS state a frame) and
R3D_NOGRAIN for measuring.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

packages/ludic.render3d/shaders/overlay.frag

@@ -6,6 +6,18 @@ in vec4 v_col;
 uniform sampler2D u_tex;
 uniform sampler2D u_font;
 out vec4 o_color;
+#ifdef HDR10
+// the interface is sRGB: drawn into an HDR10 frame it sits at paper white, as the picture's white does
+const float HDR_PAPER = 200.0;
+vec3 bt709_to_2020(vec3 c) {
+  return mat3(0.6274, 0.0691, 0.0164, 0.3293, 0.9195, 0.0880, 0.0433, 0.0114, 0.8956) * c;
+}
+vec3 pq_encode(vec3 nits) {
+  const float m1 = 0.1593017578125, m2 = 78.84375, c1 = 0.8359375, c2 = 18.8515625, c3 = 18.6875;
+  vec3 yp = pow(clamp(nits / 10000.0, 0.0, 1.0), vec3(m1));
+  return pow((c1 + c2 * yp) / (1.0 + c3 * yp), vec3(m2));
+}
+#endif
 void main() {
   float mode = floor((v_uv.y + 0.5) * 0.25);
   vec2 uv = vec2(v_uv.x, v_uv.y - 4.0 * mode);
@@ -17,4 +29,7 @@ void main() {
     vec4 t = texture(u_tex, uv);
     o_color = vec4(v_col.rgb * t.rgb, v_col.a * t.a);
   }
+#ifdef HDR10
+  o_color.rgb = pq_encode(bt709_to_2020(pow(max(o_color.rgb, vec3(0.0)), vec3(2.2))) * HDR_PAPER);
+#endif
 }