Proposal: Integrate TypeScript Definitions into `basic-auth`

[Phillip9587]

Summary

Currently, TypeScript users of basic-auth rely on the external @types/basic-auth package for type definitions. To improve maintainability, developer experience, and ensure type definitions stay in sync with the library, this proposal suggests migrating the type definitions directly into the basic-auth package.

Benefits

• Improved Maintainability: Type definitions will be updated alongside the core library, reducing the risk of outdated or mismatched types.
• Better Developer Experience: Users won’t need to install an additional @types/basic-auth package.
• Increased Adoption: Built-in types may encourage more developers to use the library with TypeScript.

Proposed Changes

1. Add a index.d.ts file with the current type definitions from @types/basic-auth.
2. Update package.json to include "types": "index.d.ts".
3. Ensure types align with the latest API and are well-documented.
4. Remove the need for @types/basic-auth and update documentation accordingly.
5. Deprecate @types/basic-auth