test: migrate math/base/special/csc to ULP-based assertions

[Planeshifter]

Resolves a part of #11352.

Description

What is the purpose of this pull request?

This pull request:

• Migrates math/base/special/csc testing from EPS-based relative tolerance assertions to @stdlib/assert/is-almost-same-value ULP difference assertions.
• Tightens each fixture range to the minimum required ULP tolerance, measured by running the fixture set against the implementation:
  • huge_negative / huge_positive: 2 ULP
  • very_large_negative / very_large_positive: 1 ULP
  • large, medium, small, smaller, tiny (negative/positive): exact match (0 ULP), so these now use plain t.strictEqual, matching the convention used in already-migrated sibling packages (e.g. coth, havercos) for ranges that never require tolerance.
• Applied the identical change to test.native.js, keeping the same ULP bounds as test.js.
• Measured minimums were confirmed deterministic by running the full fixture set twice.

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.

No.

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 by Claude Code, run as a scheduled/autonomous task. It studied issue #11352 and several already-merged sibling PRs (coth, tanh, besselj0) to mirror the settled idiom, then measured the minimum passing ULP bound per fixture range directly against the implementation.

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@stdlib-js/reviewers

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Generated by Claude Code

[stdlib-bot]

Hello! 👋

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Now that you've made a few contributions, we suggest no longer working on good first issues. Instead, we encourage you to prioritize cleaning up any PRs which have yet to be merged and then proceed to work on more involved tasks.

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[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
math/base/special/csc	$\\color{green}175/175$ $\\color{green}+100.00\\%$	$\\color{green}5/5$ $\\color{green}+100.00\\%$	$\\color{green}2/2$ $\\color{green}+100.00\\%$	$\\color{green}175/175$ $\\color{green}+100.00\\%$

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