test: demonstrate a HybridFunction performance regression (DO NOT MERGE)

[mrousavy]

Performance regression canary — DO NOT MERGE

This draft PR intentionally adds 128 rounds of dependent unsigned arithmetic to
each HybridFunction native-state lookup. Volatile local storage keeps the work
in optimized Release builds without shared state, sleeps, allocations, or altered
return values. Closing this PR discards the entire experiment.

The base is the top of the infrastructure stack, including the version-alignment
PR. Both base and head already contain the same benchmark app and definitions.
CI must build both binaries independently and run the existing ABBA sequence.
The suite hash must remain identical; this is not a rebaseline or an A/A run.

Expected observations:

• C++ and Swift/Kotlin primitive calls and property access get slower.
• JS and TurboModule controls do not execute this extra work.
• Expensive operations can show a much smaller relative change.
• Promise metrics remain advisory. Performance verdicts overall remain advisory;
  a detected regression does not imply that the build check should turn red.

End-to-end validation checks the real GitHub Actions artifacts, confirms base
and head SHAs and matching suite hashes, inspects the paired PR comment, and
verifies Bencher reports for both platform testbeds and this PR branch. Bencher
publishing requires the rotated project key in BENCHER_KEY and
NITRO_BENCHER_ENABLED=true; the paired PR comment is independent of that key.

Reporting fixes belong in the infrastructure PR, not in this canary diff. Keep
this PR draft and never merge its intentional production slowdown.

First paired CI result

Run 33898772711
built both revisions independently and completed six base/head suites per
platform, including the one permitted noise retry. Both sides used Release
Nitro, Hermes, and the same benchmark-suite hash.

• Android C++ addNumbers: 173.6 ns/op → 621.4 ns/op (+258%, 95% CI
  +247%…+261%). The JS control changed -0.6%; the TurboModule control remained
  inconclusive.
• iOS C++ addNumbers: 161.5 ns/op → 450.5 ns/op (+179%, 95% CI
  +154%…+211%). The first reporter called every synchronous iOS case noisy
  because its robust CV exceeded 5%, even when the paired interval was
  decisive.

That result exposed a reporting-policy bug rather than a sampling failure. The
infrastructure PR now lets a change whose full paired confidence interval is
beyond the budget keep its regression/improvement verdict. CV still produces a
neutral result when the interval cannot decide. Rebuilding the report from the
same raw samples yields 29 Android and 25 iOS regressions while leaving the JS
and TurboModule controls neutral.

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Nitro performance

Performance changes are advisory while the baseline is being calibrated.

Android

Benchmark	Base	Head	Δ	95% CI	Status
javascript/control/add-numbers	26.1 ns	26.4 ns	1.15%	-2.37%…5.02%	⚪ unchanged
nitro-cpp/array-buffer/bounce-1-mib	558.4 ns	633.2 ns	13.40%	2.25%…22.09%	🔴 regression
nitro-cpp/array-buffer/bounce-4-kib	546.7 ns	634.2 ns	16.00%	4.42%…23.42%	🔴 regression
nitro-cpp/array-buffer/copy-1-mib	15.44 µs	15.57 µs	0.86%	-0.90%…1.65%	⚪ unchanged
nitro-cpp/array-buffer/copy-4-kib	961.4 ns	1.04 µs	7.76%	2.04%…12.37%	🔴 regression
nitro-cpp/array/large-1024	40.51 µs	41.17 µs	1.64%	-2.90%…3.42%	⚪ unchanged
nitro-cpp/array/small-16	872.0 ns	978.3 ns	12.20%	8.75%…14.22%	🔴 regression
nitro-cpp/callback/synchronous	422.6 ns	490.8 ns	16.16%	10.67%…26.12%	🔴 regression
nitro-cpp/hybrid-object/create	696.4 ns	871.1 ns	25.09%	22.66%…30.51%	🔴 regression
nitro-cpp/hybrid-object/return-existing	247.6 ns	464.9 ns	87.77%	83.23%…90.86%	🔴 regression
nitro-cpp/map/typed-eight-entries	1.90 µs	2.03 µs	6.60%	2.23%…9.94%	🔴 regression
nitro-cpp/optional/trailing-string	160.1 ns	277.5 ns	73.39%	69.24%…76.11%	🔴 regression
nitro-cpp/primitive/add-numbers	101.0 ns	214.0 ns	111.97%	105.62%…114.95%	🔴 regression
nitro-cpp/primitive/simple-func	85.9 ns	196.2 ns	128.36%	122.17%…136.32%	🔴 regression
nitro-cpp/promise/immediate	961.8 ns	1.05 µs	9.05%	6.51%…13.18%	ℹ️ advisory
nitro-cpp/property/number-get-set	176.6 ns	387.8 ns	119.55%	113.28%…126.21%	🔴 regression
nitro-cpp/string/ascii-short	157.7 ns	265.6 ns	68.49%	66.08%…71.74%	🔴 regression
nitro-cpp/string/unicode	281.7 ns	394.8 ns	40.14%	36.93%…41.59%	🔴 regression
nitro-cpp/struct/nested-car	2.34 µs	2.53 µs	8.20%	4.41%…10.63%	🔴 regression
nitro-cpp/variant/number-or-string	149.1 ns	256.9 ns	72.35%	70.67%…75.73%	🔴 regression
nitro-platform/array-buffer/bounce-1-mib	1.52 µs	1.53 µs	0.44%	-3.59%…7.46%	🟡 noisy
nitro-platform/array-buffer/bounce-4-kib	1.53 µs	1.57 µs	2.90%	-4.21%…11.94%	🟡 noisy
nitro-platform/array-buffer/copy-1-mib	316.75 µs	313.89 µs	-0.90%	-3.77%…2.53%	🟡 noisy
nitro-platform/array-buffer/copy-4-kib	5.26 µs	5.30 µs	0.75%	-3.71%…5.10%	🟡 noisy
nitro-platform/array/large-1024	46.54 µs	46.20 µs	-0.73%	-2.85%…1.02%	⚪ unchanged
nitro-platform/array/small-16	1.23 µs	1.33 µs	8.71%	6.76%…11.64%	🔴 regression
nitro-platform/callback/synchronous	1.19 µs	1.25 µs	5.85%	2.17%…11.10%	🔴 regression
nitro-platform/hybrid-object/create	2.05 µs	2.20 µs	7.21%	1.82%…13.88%	🔴 regression
nitro-platform/hybrid-object/return-existing	649.4 ns	851.9 ns	31.18%	29.51%…35.05%	🔴 regression
nitro-platform/map/typed-eight-entries	7.99 µs	8.19 µs	2.46%	-0.61%…5.71%	⚪ unchanged
nitro-platform/optional/trailing-string	388.3 ns	488.0 ns	25.70%	22.88%…28.77%	🔴 regression
nitro-platform/primitive/add-numbers	133.5 ns	240.0 ns	79.74%	77.09%…84.45%	🔴 regression
nitro-platform/primitive/simple-func	108.0 ns	215.8 ns	99.84%	96.25%…103.62%	🔴 regression
nitro-platform/promise/immediate	2.76 µs	2.85 µs	3.44%	1.60%…7.48%	ℹ️ advisory
nitro-platform/property/number-get-set	252.6 ns	469.0 ns	85.69%	81.69%…89.91%	🔴 regression
nitro-platform/string/ascii-short	550.8 ns	668.4 ns	21.36%	17.61%…23.17%	🔴 regression
nitro-platform/string/unicode	873.5 ns	979.1 ns	12.08%	4.61%…18.38%	🔴 regression
nitro-platform/struct/nested-car	5.33 µs	5.45 µs	2.23%	0.64%…4.17%	⚪ unchanged
nitro-platform/variant/number-or-string	477.7 ns	589.0 ns	23.31%	19.17%…25.98%	🔴 regression
turbo-module/control/add-numbers	263.5 ns	258.9 ns	-1.74%	-4.63%…5.43%	⚪ unchanged

iOS

Benchmark	Base	Head	Δ	95% CI	Status
javascript/control/add-numbers	42.9 ns	39.1 ns	-9.01%	-11.99%…23.14%	🟡 noisy
nitro-cpp/array-buffer/bounce-1-mib	463.0 ns	771.1 ns	66.54%	46.92%…97.81%	🔴 regression
nitro-cpp/array-buffer/bounce-4-kib	507.0 ns	857.1 ns	69.03%	46.01%…93.14%	🔴 regression
nitro-cpp/array-buffer/copy-1-mib	103.87 µs	117.01 µs	12.65%	2.77%…54.26%	🔴 regression
nitro-cpp/array-buffer/copy-4-kib	1.92 µs	2.41 µs	25.40%	-8.41%…60.46%	🟡 noisy
nitro-cpp/array/large-1024	75.55 µs	79.47 µs	5.18%	-15.89%…23.52%	🟡 noisy
nitro-cpp/array/small-16	1.60 µs	1.91 µs	19.84%	6.62%…31.52%	🔴 regression
nitro-cpp/callback/synchronous	384.4 ns	712.8 ns	85.45%	44.88%…174.67%	🔴 regression
nitro-cpp/hybrid-object/create	747.4 ns	1.52 µs	103.08%	41.66%…127.38%	🔴 regression
nitro-cpp/hybrid-object/return-existing	347.3 ns	1.08 µs	209.83%	139.31%…235.80%	🔴 regression
nitro-cpp/map/typed-eight-entries	2.90 µs	3.85 µs	32.78%	7.60%…57.19%	🔴 regression
nitro-cpp/optional/trailing-string	287.0 ns	653.1 ns	127.51%	111.88%…150.47%	🔴 regression
nitro-cpp/primitive/add-numbers	167.8 ns	425.5 ns	153.59%	143.13%…193.96%	🔴 regression
nitro-cpp/primitive/simple-func	143.0 ns	441.8 ns	209.00%	189.90%…235.80%	🔴 regression
nitro-cpp/promise/immediate	1.62 µs	1.89 µs	16.91%	-10.40%…66.01%	ℹ️ advisory
nitro-cpp/property/number-get-set	290.7 ns	869.9 ns	199.26%	182.71%…252.50%	🔴 regression
nitro-cpp/string/ascii-short	260.3 ns	452.8 ns	73.95%	65.27%…131.52%	🔴 regression
nitro-cpp/string/unicode	512.8 ns	863.7 ns	68.42%	35.23%…78.13%	🔴 regression
nitro-cpp/struct/nested-car	4.08 µs	4.49 µs	9.95%	0.08%…17.02%	🔴 regression
nitro-cpp/variant/number-or-string	261.0 ns	508.1 ns	94.65%	58.19%…146.22%	🔴 regression
nitro-platform/array-buffer/bounce-1-mib	526.4 ns	819.7 ns	55.71%	33.72%…71.33%	🔴 regression
nitro-platform/array-buffer/bounce-4-kib	456.1 ns	848.1 ns	85.95%	35.27%…95.78%	🔴 regression
nitro-platform/array-buffer/copy-1-mib	122.46 µs	94.94 µs	-22.47%	-33.54%…24.12%	🟡 noisy
nitro-platform/array-buffer/copy-4-kib	1.99 µs	2.48 µs	24.54%	-1.98%…51.57%	🟡 noisy
nitro-platform/array/large-1024	70.32 µs	84.49 µs	20.15%	-10.74%…28.47%	🟡 noisy
nitro-platform/array/small-16	1.51 µs	2.07 µs	37.40%	0.68%…47.95%	🔴 regression
nitro-platform/callback/synchronous	514.7 ns	811.6 ns	57.69%	22.44%…76.59%	🔴 regression
nitro-platform/hybrid-object/create	37.19 µs	45.34 µs	21.89%	6.60%…34.28%	🔴 regression
nitro-platform/hybrid-object/return-existing	435.6 ns	1.01 µs	131.82%	118.39%…163.91%	🔴 regression
nitro-platform/map/typed-eight-entries	3.55 µs	4.80 µs	35.41%	-15.75%…59.44%	🟡 noisy
nitro-platform/optional/trailing-string	274.7 ns	624.4 ns	127.32%	84.40%…163.18%	🔴 regression
nitro-platform/primitive/add-numbers	141.0 ns	455.7 ns	223.13%	125.74%…247.24%	🔴 regression
nitro-platform/primitive/simple-func	118.4 ns	390.8 ns	229.93%	137.52%…302.17%	🔴 regression
nitro-platform/promise/immediate	2.52 µs	2.61 µs	3.62%	-26.17%…42.87%	ℹ️ advisory
nitro-platform/property/number-get-set	260.3 ns	867.3 ns	233.15%	95.68%…274.13%	🔴 regression
nitro-platform/string/ascii-short	292.7 ns	585.5 ns	100.01%	61.00%…145.07%	🔴 regression
nitro-platform/string/unicode	615.1 ns	1.04 µs	68.76%	13.13%…89.97%	🔴 regression
nitro-platform/struct/nested-car	3.55 µs	4.52 µs	27.51%	-18.73%…34.67%	🟡 noisy
nitro-platform/variant/number-or-string	330.9 ns	641.8 ns	93.97%	40.91%…140.49%	🔴 regression
turbo-module/control/add-numbers	1.79 µs	1.80 µs	0.19%	-10.53%…17.71%	🟡 noisy

_{Base 8ed1f9be · Head 144e2c61 · lower is better}