Add TypeScript Type Declarations

[andrii-bodnar]

🚀 Feature Proposal

Currently, i18nextify lacks official TypeScript type declarations, which makes it harder to use in TypeScript projects. We should add proper type declarations similar to how it's done in the i18next repository.

Motivation

• No official type declarations are provided
• Users need to create their own type declarations
• Type safety is not guaranteed when using the library

Benefits

1. Better TypeScript integration
2. Improved developer experience with autocomplete
3. Catch potential errors at compile time
4. Better documentation through types

References

• i18next TypeScript declarations

[adrai]

If you're ok with maintaining the typescript support for i18nextify, feel free to open a PR.