Collect AMD amdgpu sysfs and optional NVIDIA nvidia-smi stats in the
background, auto-detecting supported adapters in PCI order and rotating
additional pairs alongside CPU/RAM. Explicit PCI selection and off mode
remain supported; missing metrics render as N/A.
Initialize the bitmap-only canvas locally instead of the ABI-dependent
libg15render initializer: the installed TTF-enabled renderer wrote an
8-byte FreeType pointer past the smaller bitmap-only allocation, corrupting
the heap before GPU threads started. Add collector, rendering and full-main
regression tests.
Mikhail Yevchenko