Permanent frame profiler: FrameBoundary() at the top of OnRender measures
CPU frame time (swap-to-swap delta), brackets the frame in a GpuFrameTimer
TimeElapsed query (self-disabled under ACDREAM_WB_DIAG=1), and samples
per-frame allocated bytes + GC collection deltas. BeginStage(FrameStage)
scopes attribute CPU time to Update/Upload/ImGui. Emits one [frame-prof]
report line every ~5s while RenderingDiagnostics.FrameProfEnabled is on;
zero-cost stage scopes when off. Report formatting is a pure static
method, unit-tested for invariant-culture formatting and the gpu=off
fallback text.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
