Tasks C, H, I from the plan:
- Forgiving API key validation: add Printify UUID format and Printful
length validation, validate on blur for fast feedback, helpful error
messages with specific guidance
- External links UX: verified all external links use <.external_link>
component with target="_blank", rel="noopener noreferrer", icon, and
screen reader text
- Input styling WCAG compliance: increase input border contrast from
~3.3:1 to ~4.5-5:1 across all theme moods (neutral, warm, cool, dark)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
