Config: Add shared Prettier config as a published subpath

[PetarStoev02]

Context

Each repo in the org currently maintains its own Prettier configuration. Pulling this into @w3-kit/config as a published subpath (e.g., @w3-kit/config/prettier) gives every repo a single source of truth and a one-line consumption pattern.

What to build

Add a prettier.config.cjs (or .json) to this repo exporting the project's preferred Prettier settings, then expose it via the package's exports map under ./prettier. Update the README to show how to consume it from any downstream repo:

// prettier.config.js
module.exports = require('@w3-kit/config/prettier')

Acceptance criteria

• Prettier config exported from @w3-kit/config/prettier
• package.json exports field updated
• README documents consumption pattern
• Existing TS/ESLint configs continue to work
• New patch version published (or bump pending) to npm

Pointers

• Reference: existing tsconfig / eslint exports in this repo
• Related: config Add reusable GitHub Actions workflows #2 (reusable workflows — similar shared-resource idea)

Complexity

🟢 Good first issue

[peter941221]

I'd like to work on this.