feat: add TypeScript types for bigint.js

[Copilot]

• Create bigint.d.ts type definition file
• Add types export to package.json exports for ./bigint.js
• Add bigint.d.ts to package.json files list
• Run tests to verify types work correctly
• Address code review feedback on type overloads
• Simplify type definitions for better readability
• Run security checks (0 issues found)
• Document endianness in type definitions
• Sync README.md with type definitions
• Rename parameter for consistency
• Complete task

Original prompt

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This section details on the original issue you should resolve

<issue_title>Types: bigint.js</issue_title>
<issue_description>Add types for /bigint.js</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Types: bigint.js #20

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[ChALkeR]

@copilot Sync README.md @exodus/bytes/bigint.js section with this.

[Copilot]

@copilot Sync README.md @exodus/bytes/bigint.js section with this.

Done. Synced the README.md bigint.js section with the type definitions, including descriptions, big-endian format documentation, and error conditions (43f57dc).

[Copilot]

Pull request overview

Adds first-class TypeScript typings for @exodus/bytes/bigint.js, and wires them into package exports/documentation.

Changes:

• Added bigint.d.ts with overloads for fromBigInt / toBigInt and documented big-endian behavior
• Updated package.json files + exports to publish and expose the new typings for ./bigint.js
• Updated README section for @exodus/bytes/bigint.js to match the typed API and endianness docs

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated no comments.

File	Description
package.json	Publishes bigint.d.ts and exposes it via exports["./bigint.js"].types
bigint.d.ts	Introduces TypeScript definitions for BigInt ↔ bytes conversions
README.md	Expands module docs to reflect behavior and endianness

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