test: migrate stats/incr/mstdev to ULP-based assertions

[kgryte]

Resolves a part of #11352.

Description

What is the purpose of this pull request?

This pull request:

• migrates the tests for stats/incr/mstdev from relative tolerance testing to ULP difference testing, replacing the computed delta/tol comparisons with isAlmostSameValue.
• uses a ULP bound of 0 for both converted assertions, which is the measured minimum: the accumulated moving corrected sample standard deviations in the fixture set are bit-for-bit equal to the expected values, so no non-zero ULP budget is required. Starting from a bound of 64 and tightening, 0 is the smallest integer for which the full fixture set passes, and the suite was run twice at 0 to confirm determinism.
• removes the now unused @stdlib/math/base/special/abs and @stdlib/constants/float64/eps requires from the test file.

Only test/test.js is modified; the package has no test/test.native.js. Existing exact comparisons (e.g., the t.deepEqual fixture checks and the t.strictEqual NaN/null checks) are left untouched.

Related Issues

Does this pull request have any related issues?

This pull request has the following related issues:

• [RFC]: Migrate math/base/special packages from relative tolerance testing to ULP difference testing (tracking issue) #11352

Questions

Any questions for reviewers of this pull request?

No.

Other

Any other information relevant to this pull request? This may include screenshots, references, and/or implementation notes.

• Final ULP constant: 0 (measured minimum). The per-assertion ULP distances were measured directly via @stdlib/number/float64/base/ulp-difference as 0 and 0, respectively.
• make test TESTS_FILTER=".*/stats/incr/mstdev/.*" is green on two consecutive runs, 396/396 assertions passing.
• make lint-javascript-tests TESTS_FILTER=".*/stats/incr/mstdev/.*" is clean.

Checklist

Please ensure the following tasks are completed before submitting this pull request.

• Read, understood, and followed the contributing guidelines.

AI Assistance

When authoring the changes proposed in this PR, did you use any kind of AI assistance?

• Yes
• No

If you answered "yes" above, how did you use AI assistance?

• Code generation (e.g., when writing an implementation or fixing a bug)
• Test/benchmark generation
• Documentation (including examples)
• Research and understanding

Disclosure

This PR was authored by Claude Code running as an unattended scheduled task: it selected the package, performed the test migration, measured the minimum ULP bound, and ran the tests and linter.

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@stdlib-js/reviewers

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Generated by Claude Code

[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
stats/incr/mstdev	$\\color{green}367/367$ $\\color{green}+100.00\\%$	$\\color{green}53/53$ $\\color{green}+100.00\\%$	$\\color{green}3/3$ $\\color{green}+100.00\\%$	$\\color{green}367/367$ $\\color{green}+100.00\\%$

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