chore(bara): combine internal package and publish as bara module

- [ ] Anyone can be use each Bara package independently.
- [ ] `@barajs/core`: The heart of Bara.
- [ ] `@barajs/formula`: Bara functional programming library.
- [ ] Short name for simple and memorable usage.

Start by examining the repository structure and the `@barajs/core` and `@barajs/formula` packages. Determine how they could be combined and what shorter module name is intended; the work is done when the package organization and publishing approach are defined and both listed goals are addressed.

Written by the indexing model from the issue text.