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

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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.