r3d_hdr_calibrate(peak, paper, black) feeds the tonemap's and the overlay's HDR10 variants and
the display's HDR metadata; ov_hdr_nits draws a calibration patch at a number of nits.
gpu_caps_probe asks the running Vulkan renderer's instance instead of making and destroying a
second one under Streamline's interposer, which left the next swapchain rebuild calling address 0.
The overlay gets an HDR10 variant, and the tonemap brightens HDR highlights by one factor rather
than per channel.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
