feat: add constants/float16/sqrt-half-pi

[opbot-xd]

Description

What is the purpose of this pull request?

This pull request:

• adds @stdlib/constants/float16/sqrt-half-pi, which provides the square root of π/2 as a half-precision floating-point number

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? This may include screenshots, references, and/or implementation notes.

• Float64 value: 1.2533141373155001...
• Float16 value: 1.2529296875

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

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Coverage Report

Package	Statements	Branches	Functions	Lines
constants/float16/sqrt-half-pi	$\color{green}48/48$ $\color{green}+0.00%$	$\color{green}1/1$ $\color{green}+0.00%$	$\color{green}0/0$ $\color{green}+0.00%$	$\color{green}48/48$ $\color{green}+0.00%$

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