Convert button-style workflow links to Card components

[mintlify]

Summary

Converts all inline-styled anchor buttons to Mintlify Card components across tutorial documentation.

Changes (76 files):

• Cloud buttons (purple/green with cloud.comfy.org URLs) → <Card icon="cloud">
• Download buttons (blue with raw.githubusercontent.com URLs) → <Card icon="download">
• Button pairs wrapped in <CardGroup cols={2}>
• Cloud card positioned first (left), download second (right)
• Applied to both English and Chinese versions

Example before:

<a href="https://cloud.comfy.org/..." style={{ display: 'inline-block', backgroundColor: '#28A745', ... }}>
    Run on Comfy Cloud
</a>
<a href="https://raw.githubusercontent.com/..." style={{ display: 'inline-block', backgroundColor: '#0078D6', ... }}>
    Download JSON Workflow
</a>

Example after:

<CardGroup cols={2}>
  <Card title="Run on Comfy Cloud" icon="cloud" href="...">
    Open this workflow directly in Comfy Cloud
  </Card>
  <Card title="Download Workflow" icon="download" href="...">
    Download the JSON workflow file for local use
  </Card>
</CardGroup>