feat: add symbol/split

[WillyEverGreen]

Resolves #8488.

Description

This pull request adds the @stdlib/symbol/split package, which provides access to
the well-known Symbol.split symbol in environments that support it and null
otherwise.

The package follows established stdlib conventions and includes documentation,
examples, tests, REPL help text, TypeScript definitions, and namespace integration.

Related Issues

• [RFC]: add symbol/split #8488

Questions

No.

Other

Implementation Notes

The package structure follows existing conventions established by similar stdlib
packages, including:

• @stdlib/symbol/replace
• @stdlib/symbol/has-instance
• @stdlib/symbol/is-concat-spreadable

Files Added

File	Description
lib/node_modules/@stdlib/symbol/split/lib/main.js	Main implementation exporting Symbol.split or null
lib/node_modules/@stdlib/symbol/split/lib/index.js	Module entry point
lib/node_modules/@stdlib/symbol/split/test/test.js	Unit tests
lib/node_modules/@stdlib/symbol/split/examples/index.js	Usage examples
lib/node_modules/@stdlib/symbol/split/README.md	Package documentation
lib/node_modules/@stdlib/symbol/split/package.json	Package metadata
lib/node_modules/@stdlib/symbol/split/docs/repl.txt	REPL help text
lib/node_modules/@stdlib/symbol/split/docs/types/index.d.ts	TypeScript definitions
lib/node_modules/@stdlib/symbol/split/docs/types/test.ts	TypeScript tests

Files Modified

File	Description
lib/node_modules/@stdlib/symbol/lib/index.js	Added SplitSymbol to the symbol namespace

Test Results

All tests pass.

Checklist

• Read, understood, and followed the contributing guidelines.

AI Assistance

• Yes
• No

Disclosure:
AI assistance was used to generate the initial implementation, tests, and
documentation based on existing stdlib symbol packages. I reviewed the generated
code, verified its behavior locally, ensured it follows project conventions, and
take responsibility for this contribution.

@stdlib-js/reviewers

[stdlib-bot]

Hello! Thank you for your contribution to stdlib.

We noticed that the contributing guidelines acknowledgment is missing from your pull request. Here's what you need to do:

1. Please read our contributing guidelines.

2. Update your pull request description to include this checked box:

   - [x] Read, understood, and followed the [contributing guidelines](https://github.com/stdlib-js/stdlib/blob/develop/CONTRIBUTING.md)

This acknowledgment confirms that you've read the guidelines, which include:

• The developer's certificate of origin
• Your agreement to license your contributions under the project's terms

We can't review or accept contributions without this acknowledgment.

Thank you for your understanding and cooperation. We look forward to reviewing your contribution!

[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
symbol	$\color{green}929/929$ $\color{green}+0.00%$	$\color{red}17/25$ $\color{green}+0.00%$	$\color{green}0/0$ $\color{green}+0.00%$	$\color{green}929/929$ $\color{green}+0.00%$
symbol/split	$\color{green}92/92$ $\color{green}+0.00%$	$\color{red}2/3$ $\color{green}+0.00%$	$\color{green}0/0$ $\color{green}+0.00%$	$\color{green}92/92$ $\color{green}+0.00%$

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

[WillyEverGreen]

Hi @kgryte,
Just a gentle ping on this PR when you have time.
All checks are passing and this implements RFC #8488 following existing symbol package conventions.
Happy to make any changes if needed. Thanks!