test: migrate math/base/special/kernel-tan to ULP-based testing

[Planeshifter]

Resolves a part of #11352.

Description

What is the purpose of this pull request?

This pull request:

• migrates test/test.native.js for math/base/special/kernel-tan from relative-tolerance (EPS-based) assertions to ULP-difference assertions via @stdlib/assert/is-almost-same-value, using the minimum required ULP value (1) for each of the three fixture-driven test blocks. The minimum ULP values were determined by direct ULP-difference computation (via @stdlib/number/float64/base/ulp-difference) over all fixture cases against the built native addon and independently re-verified.
• leaves test/test.js unchanged: the JavaScript test file already used exact t.strictEqual( out, expected[ i ], ... ) assertions, and the measured maximum ULP difference for the JavaScript implementation is 0 across all fixture cases, so exact equality assertions are retained per maintainer guidance.
• since the native (C) results diverge from the JavaScript results (native maximum ULP difference of 1 versus 0 for JavaScript), the canonical NOTE comment regarding compiler optimizations (see feat: add C implementation for math/base/special/spence #2298 (comment)) is retained above each migrated assertion, as in the pre-migration code.

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.

• Minimality was verified: with a ULP tolerance of 0, native assertions fail; with 1, all 3008 tests pass via the official test harness (make test).

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

If you answered "yes" to using AI assistance, please provide a short disclosure indicating how you used AI assistance. This helps reviewers determine how much scrutiny to apply when reviewing your contribution. Example disclosures: "This PR was written primarily by Claude Code." or "I consulted ChatGPT to understand the codebase, but the proposed changes were fully authored manually by myself.".

This PR was written primarily by Claude Code, which performed the test migration, computed the minimum ULP tolerances against the test fixtures, and verified the results; an independent automated verification pass re-computed the ULP values before opening this PR.

---

@stdlib-js/reviewers

[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
math/base/special/kernel-tan	$\\color{red}394/398$ $\\color{green}+99.00\\%$	$\\color{red}15/17$ $\\color{green}+88.24\\%$	$\\color{green}4/4$ $\\color{green}+100.00\\%$	$\\color{red}394/398$ $\\color{green}+99.00\\%$

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