Point default import to ./bundler/dom.json and update README

[mattpocock]

Summary

• Update the exports field in package.json so the default import (@total-typescript/tsconfig) points to ./bundler/dom.json.
• Update the README.md to clarify that the default import is now the bundler DOM app config.

Proposed Changes

package.json

• Add or update the entry in exports:

  ".": "./bundler/dom.json"

README.md

• Add a section under Default Import to explain that @total-typescript/tsconfig now points to bundler/dom.json, and provide a usage example.
• Clarify that this is equivalent to extending @total-typescript/tsconfig/bundler/dom/app.

---

See below for the suggested file changes:

{
  ...
  "exports": {
    ".": "./bundler/dom.json",
    ...
  }
}

## Default Import

The default import of `@total-typescript/tsconfig` now points to the **bundler DOM app config** (`bundler/dom.json`). This is optimized for apps running in the DOM using an external bundler (like Vite, Remix, Astro, etc.).

For most users, you can now simply use:

```jsonc
{
  "extends": "@total-typescript/tsconfig"
}
```

This is equivalent to:

```jsonc
{
  "extends": "@total-typescript/tsconfig/bundler/dom/app"
}
```