Add bounded portal presentation performance smoke mode

[EHotwagner]

Add an explicit --presentation-performance mode to the real portal example. It disposes the five-tick setup before five warmup cycles and twenty samples of 1,200 actual interpolation/projection views. Every frame is retained and checked outside timing. Raw stopwatch, process CPU/GC and current-thread allocation observations include per-view normalization and workload/assembly identity.

One admitted fresh offline seven-package receiver at source 13a8cdeb passed unchanged locked restore, assets/nuspec checks, Release build, CLI 0/0/2 and the explicit smoke mode. All twenty raw samples and 24,000 views are retained; elapsed median was 886.82 ns/view with its outliers preserved. These remain observations of that exact source/assembly, with no historical comparison, timing threshold, steady-state or release verdict.

Seven native jobs (Ubuntu/Windows property, full-test and deterministic builds, plus surface-baseline) failed the same nullable environment-variable guard during compilation, before property tests or baseline refresh. Refine through Option.ofObj before string access. Local compilation now explicitly matches null checking, latest language and warnings-as-errors, and six compiled refusal controls pass. The measured computational body is byte-identical to 13a8cdeb; no measurement was repeated and no baseline files changed. First local and native failures are retained.

Historical baseline is unknown; P3 performance release and fresh/retained product adoption remain open. Original resume04/resume05 custody and cleanup measurement limits are unchanged. Parent owns native rerun and remote integration.