docs: improve doctests for complex number instances in array/base/at

[aryan7071]

Resolves a part of #8641

Description

What is the purpose of this pull request?

This pull request:

• Updates the documentation examples for the array/base/at package to use the new compact complex instance doctest notation.
• Removes example usage of real, imag, realf, and imagf which were previously used to decompose complex numbers into real and imaginary components.
• Replaces those decomposed return annotations with direct complex instance annotations such as:
  • // returns <Complex128>[ 1.0, 2.0 ]
  • // returns <Complex128>[ 3.0, 4.0 ]
  • // returns <Complex128>[ 5.0, 6.0 ]
  • // returns <Complex64>[ 1.0, 2.0 ]
  • // returns <Complex64>[ 3.0, 4.0 ]
  • // returns <Complex64>[ 5.0, 6.0 ]
• Ensures consistency with the recent RFC and the updated doctest framework which now supports complex instance notation.

Related Issues

Does this pull request have any related issues?

This pull request has the following related issues:

• [RFC]: Improve doctests for complex number instances in documentation examples (tracking issue) #8641

(Replace the placeholder above with the actual issue number.)

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.
• Updated only the examples for the array/base/at package.
• Ensured no functional code was modified.
• Followed the doctest formatting conventions described in the RFC.

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.

Only for research purpose , else everything i done it myself

---

@stdlib-js/reviewers

[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
array/base/at	$\color{green}138/138$ $color{green}+100.00%$	$\color{green}9/9$ $color{green}+100.00%$	$\color{green}2/2$ $color{green}+100.00%$	$\color{green}138/138$ $color{green}+100.00%$

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

[stdlib-bot]

⚠️ Tracking Issue Closure Warning ⚠️

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Why this matters:
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Required action:
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Thank you for your contribution to the project!

[kgryte]

LGTM after clean-up