feat: add stats/incr/mskewness

[sagar7162]

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Resolves #15.

Description

What is the purpose of this pull request?

This pull request:

• adds stats/incr/mskewness

Related Issues

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This pull request has the following related issues:

• #{{TODO: add related issue number}}

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No.

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• Read, understood, and followed the contributing guidelines.

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@stdlib-js/reviewers

[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
stats/incr/mskewness	$\color{green}280/280$ $\color{green}+0.00%$	$\color{red}26/28$ $\color{green}+0.00%$	$\color{green}2/2$ $\color{green}+0.00%$	$\color{green}280/280$ $\color{green}+0.00%$

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

[sagar7162]

/stdlib update-copyright-years

[stdlib-bot]

/stdlib update-copyright-years

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[Planeshifter]

@sagar7162 we might need to pull in latest changes first via e.g. /stdlib merge.

[sagar7162]

/stdlib merge

[sagar7162]

/stdlib update-copyright-years

[stdlib-bot]

/stdlib update-copyright-years

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[Planeshifter]

Bug: when W=1, the sliding window branch computes ( N * mean - v ) / ( N - 1 ) which divides by zero. Need a guard for N === 1 (or better, W < 3 since skewness is undefined for fewer than 3 values). Compare how incrmvariance handles the N === 1 case with a dedicated branch.

[Planeshifter]

Line 29 says "all future invocations" but this is a moving accumulator — NaN recovers after the window slides past. Should say "at least W-1 future invocations" to match the README wording.

[Planeshifter]

Missing "moving" qualifier. Should read "an updated moving corrected sample skewness" and "the current moving corrected sample skewness" per the convention in incrmvariance.

[Planeshifter]

Missing the standard note about initial window behavior. Add: "As W values are needed to fill the window buffer, the first W-1 returned values are calculated from smaller sample sizes. Until the window is full, each returned value is calculated from all provided values." See incrmvariance README.

[Planeshifter]

NaN test coverage is too thin. At minimum: (a) verify acc() (no-arg call) also returns NaN at each step; (b) test NaN at different window positions with recovery; (c) test consecutive NaN values. Model after the incrmvariance NaN tests.