Internationalization (i18n) and font rendering for CJK characters in marketing overlays. Goldie's `frame` command fails to render Chinese text correctly in headlines/subheads due to font stack limitations within the Node canvas environment.

### Description

When generating App Store screenshots with `goldie frame`, **Chinese text in the marketing overlay** (headline and subhead, outside the device mockup) fails to render correctly and appears as **tofu boxes, missing glyphs, or garbled characters**.

Text **inside the captured app screenshot renders fine** — only the headline/subhead added by Goldie’s framing layer is affected.

### Environment

- goldie: `0.2.1`
- macOS
- Node 20.x
- locale: `zh-CN`
- device: `iphone-6.9`

### Steps to Reproduce

1. Use the default font stack in `goldie.config.ts`:

```ts
theme: {
fontFamily: '-apple-system, "SF Pro Display", system-ui, sans-serif',
},
scenes: [{
headline: { "zh-CN": "反向打卡，不打卡就是成功" },
subhead: { "zh-CN": "只在破戒时记录，让戒除更轻松" },
}]
```

2. Capture screenshots, then run `goldie frame`
3. Open `out/screenshots/6.9/zh-CN/*.png`

### Expected Behavior

Headline and subhead display readable Simplified Chinese.

### Actual Behavior

Chinese characters render as tofu boxes or garbled text. For example, `反向打卡，不打卡就是成功` is not rendered correctly.

### Additional Notes

- Marketing copy is rendered with `@napi-rs/canvas`. The default `-apple-system` / `SF Pro Display` stack does not appear to resolve to a CJK-capable font in the Node canvas environment.
- Goldie’s bundled fonts (Lato, Montserrat, etc.) also do not support Chinese.
- If the design was edited in Studio, `goldie.design.json` overrides `fontFamily` from config, and the issue persists.