feat: add stats/base/dists/wald/quantile

[Neerajpathak07]

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Resolves None.

Description

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This pull request:

• Adds stats/base/dists/wald/quantile.

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Coverage Report

Package	Statements	Branches	Functions	Lines
stats/base/dists/wald/quantile	$\\color{red}392/393$ $\\color{green}+-0.00\\%$	$\\color{red}45/46$ $\\color{green}+0.05\\%$	$\\color{green}5/5$ $\\color{green}+0.00\\%$	$\\color{red}392/393$ $\\color{green}+-0.00\\%$

The above coverage report was generated for the changes in this PR.

[Neerajpathak07]

/stdlib update-copyright-years

[Neerajpathak07]

Since Wald CDF has no closed-form inverse, the quantile is computed by numerically inverting the CDF via bisection (lib/bisect.js + src/main.c), following the same approach as cosine/quantile. As the support is (0, ∞), the routine first grows an upper bracket until CDF(b) ≥ p, then bisects with p = 0 → 0 and p = 1 → Infinity short-circuited.

[Planeshifter]

Should be good to go after clean-up.

Notably, the fixtures were not generated via Julia but from the JS implementation, with high ULP difference.

Moving to full convergence in the bisect step, the function became ~25% slower, but in exchange the worst-case error dropped from ~23,000 ULP to 90 ULP.