`core` package - convert to typescript

[marcalexiei]

• Follow up of feat: core package build #139

The package is currently implemented primarily in JavaScript + JSDoc annotations, but it contains over 200 type errors.

Since we intend to publish it as an npm package, a build step is required to generate .d.ts declaration files.
To streamline maintenance and improve type safety, it would be more effective to migrate the codebase to TypeScript rather than continuing to rely on JSDoc annotations.