test: migrate stats/base/dists/exponential/stdev to ULP-based assertions

[kgryte]

Description

What is the purpose of this pull request?

This pull request:

• migrates the test suite for @stdlib/stats/base/dists/exponential/stdev from relative tolerance testing to ULP difference testing, as described in [RFC]: Migrate math/base/special packages from relative tolerance testing to ULP difference testing (tracking issue) #11352.
• replaces the previous EPS-scaled tolerance comparisons (delta <= tol) with isAlmostSameValue( y, expected[ i ], N ) assertions using @stdlib/assert/is-almost-same-value, and uses the message 'returns expected value' for each fixture-loop assertion.
• updates both test/test.js and test/test.native.js.

The ULP bound was tightened to the minimum integer that passes over the full fixture set. All 50 fixture values match the reference output exactly, so the minimum required ULP is:

• test/test.js: 0 ULP
• test/test.native.js: 0 ULP

The suite was run twice at the final bound to confirm determinism (no FMA/arch flakiness).

Related Issues

Does this pull request have any related issues?

This pull request has the following related issues:

• Resolves a part of [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 PR was authored primarily by Claude Code: it converted the tolerance-based fixture assertions to ULP-based assertions and measured the minimum passing ULP bound over the full fixture set.

---

@stdlib-js/reviewers

🤖 Generated with Claude Code

https://claude.ai/code/session_019Ba3VZAiNQUyCZRWJuJQqw

---

Generated by Claude Code

[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
stats/base/dists/exponential/stdev	$\\color{green}161/161$ $\\color{green}+100.00\\%$	$\\color{green}8/8$ $\\color{green}+100.00\\%$	$\\color{green}2/2$ $\\color{green}+100.00\\%$	$\\color{green}161/161$ $\\color{green}+100.00\\%$

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