docs: fix TSDoc issues in several math/base/tools declarations

[Planeshifter]

Description

What is the purpose of this pull request?

This pull request corrects documentation-only issues in TypeScript declaration files across the @stdlib/math/base/tools namespace, flagged by an audit:

• chebyshev-series / chebyshev-seriesf — remove the misleading inline // 1*T_0(1/2) + 0.5*T_1(1/2) example comments, which evaluate to 1.25 and contradict the correct // returns 0.75 annotations (the coefficients are stored in descending-degree order with constant-term half-weighting). Also drop the result-style comment misplaced on the factory(...) construction line, which returns an evaluator function rather than a value.
• evalrational / evalrationalf — correct off-by-one polynomial-degree labels in the examples (a degree-3 polynomial was labeled "degree 4"; a degree-1 polynomial "degree 2").
• hermitepoly / normhermitepoly / normhermitepolyf — add the "nonnegative" qualifier to the factory method's @param n, matching the call-signature @param n in the same file.

This PR addresses only the TypeScript declaration files. (The audit also noted some optional cross-package wording/alias-naming polish in this namespace; those purely-cosmetic items are intentionally left out.)

Related Issues

Does this pull request have any related issues?

No.

Questions

Any questions for reviewers of this pull request?

No.

Other

Any other information relevant to this pull request?

Found via a TypeScript-declaration audit of the @stdlib/math namespace.

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.

These issues were identified by an automated TypeScript-declaration audit run with Claude Code, and the fixes were prepared by Claude Code under my review.

---

@stdlib-js/reviewers

[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
math/base/tools/chebyshev-series	$\color{green}280/280$ $\color{green}+100.00\%$	$\color{green}20/20$ $\color{green}+100.00\%$	$\color{green}3/3$ $\color{green}+100.00\%$	$\color{green}280/280$ $\color{green}+100.00\%$
math/base/tools/chebyshev-seriesf	$\color{green}300/300$ $\color{green}+100.00\%$	$\color{green}20/20$ $\color{green}+100.00\%$	$\color{green}3/3$ $\color{green}+100.00\%$	$\color{green}300/300$ $\color{green}+100.00\%$
math/base/tools/evalrational	$\color{green}398/398$ $\color{green}+100.00\%$	$\color{green}39/39$ $\color{green}+100.00\%$	$\color{green}3/3$ $\color{green}+100.00\%$	$\color{green}398/398$ $\color{green}+100.00\%$
math/base/tools/evalrationalf	$\color{green}406/406$ $\color{green}+100.00\%$	$\color{green}39/39$ $\color{green}+100.00\%$	$\color{green}3/3$ $\color{green}+100.00\%$	$\color{green}406/406$ $\color{green}+100.00\%$
math/base/tools/hermitepoly	$\color{green}202/202$ $\color{green}+100.00\%$	$\color{green}12/12$ $\color{green}+100.00\%$	$\color{green}3/3$ $\color{green}+100.00\%$	$\color{green}202/202$ $\color{green}+100.00\%$
math/base/tools/normhermitepoly	$\color{green}226/226$ $\color{green}+100.00\%$	$\color{green}27/27$ $\color{green}+100.00\%$	$\color{green}3/3$ $\color{green}+100.00\%$	$\color{green}226/226$ $\color{green}+100.00\%$
math/base/tools/normhermitepolyf	$\color{green}230/230$ $\color{green}+100.00\%$	$\color{green}27/27$ $\color{green}+100.00\%$	$\color{green}3/3$ $\color{green}+100.00\%$	$\color{green}230/230$ $\color{green}+100.00\%$

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