CUDACtx's constructor writes GpuNewContext directly through
QueueSerialFinish(), unlike every other GPU backend (Vulkan, OpenGL,
D3D11/12, Metal, WebGPU, Rocprof), which all defer it via
GetProfiler().DeferItem() so it survives on-demand's per-connection
queue clear.
A profiler connecting any time after the CUDA context is created (in
practice: any time after process start) never receives GpuNewContext.
The GpuContextName message that Name() sends right after (already
correctly deferred) then crashes the server's
Worker::ProcessGpuContextName with an unregistered context id
(assert(ctx) fails; undefined behavior in release builds).
Same fix already applied to the Rocprof backend in #1336. Fixes#1171.
Includes a repro test under tests/cuda/repro/on_demand/, mirroring the
structure #1336 added for Rocprof: a minimal CUDA program that creates
an on-demand context (repro.cu/CMakeLists.txt), and a check_gpu_zones
tool that loads the resulting .tracy file and verifies the GPU context
was named and populated with zones. Verified locally: unpatched
tracy-capture crashes on the first connection attempt; patched, three
consecutive connect/disconnect cycles all succeed and check_gpu_zones
reports a named context with recorded zones.
