Package the Dracula theme as a native Pi package

Hi! Would you be interested in packaging this theme as a native Pi package?

Pi now supports distributing themes through its package system. A package can declare themes in `package.json` using the `pi.themes` manifest:

```json
{
"keywords": ["pi-package"],
"pi": {
"themes": ["./dracula.json"]
}
}
```

This would allow users to install the theme directly with Pi, for example:

```bash
pi install git:github.com/dracula/pi-coding-agent
```

instead of cloning the repository and manually symlinking `dracula.json` into `~/.pi/agent/themes/`.

Optionally, if the package were published to npm, installation could become:

```bash
pi install npm:
```

This should not require a TypeScript extension—the existing `dracula.json` can be exposed directly as a Pi theme package.

If this sounds good, I'd be happy to help make the necessary changes and submit a PR.

Start by inspecting package.json and the existing dracula.json theme. Confirm the Pi package manifest can expose that theme directly, then verify the repository installs with the documented pi install git:github.com/dracula/pi-coding-agent command and that the theme is available after installation.

Written by the indexing model from the issue text.