Fix flaky randomString bias test

[theoephraim]

The unbiased-output test for randomString() checked every charset char against a +/-30% bound. At n=10000 that bound sits at ~3.8 sigma, and with 62 chars checked on both tails it fails by pure chance roughly once every 130 runs (seen in CI: 210 vs 209.68). The old assertion also could not catch the modulo bias it guards against: a naive byte % 62 puts over-represented chars at ~195 counts, under the old 209.7 ceiling.

Replaced it with an aggregate count of the first 8 charset chars, exactly the ones modulo bias inflates. Unbiased sampling lands around 1290 (stddev ~33.5), biased around 1562, so the 1425 threshold is ~4 sigma from both: false failures drop to ~1 in 30k runs while a simulated biased sampler trips it in 20/20 trials. Kept a loose sanity check that every charset char appears at least once.

No resolver changes; the implementation's rejection sampling was already correct.

[github-actions]

The changes in this PR will be included in the next version bump.

Bump files in this PR

• fix-flaky-randomstring-test.md (view diff) (edit)

Click here if you want to add another bump file to this PR

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This comment is maintained by bumpy.

[github-actions]

📦 Bundle size

no change to bundle size

Metric	main	This PR	Δ
Total dist	5010.6 KB	5010.6 KB	—
JS	1717.9 KB	1717.9 KB	—
Sourcemaps	3216.2 KB	3216.2 KB	—
Type defs	76.6 KB	76.6 KB	—

dist/ only; native binaries are versioned separately and not counted here.

[pullfrog]

✅ No new issues found.

Reviewed changes across the test-only update to randomString() bias coverage and its release metadata.

• Targeted bias assertion: Replaces noisy per-character bounds with an aggregate check over the eight default-charset indices that naive modulo sampling overrepresents.
• Sanity coverage: Retains a low-risk assertion that every default-charset character appears in the 10,000-character sample.
• Release metadata: Records the test-only change as a no-bump entry for varlock.

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