feat: add ChallengeCard component

[satasatalight]

Pull Request

Description

Creates the challenge card component displaying the latest GPK monthly challenge.
The element takes a "name" string with the challenge name, a "desc" string for the basic description, a "tags" array of strings for the challenge tags at the bottom of the card, a "deadline" JavaScript Date object to display the deadline of the challenge and the challenge month, and a "link" string for the challenge's corresponding link.

Type of Change

• feat: New feature
• fix: Bug fix
• chore: Maintenance (dependencies, config, etc.)
• docs: Documentation only
• style: Code style (formatting, no logic change)
• refactor: Code refactor (no new feature or fix)

Changes Made

• components/ChallengeCard.tsx (created)

Screenshots (if applicable)

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my code
• I have tested my changes locally
• npm run lint passes without errors
• npm run build completes successfully

Related Issues

Closes Notion task "T10 (Challenges) - Build ChallengeCard component"

[sebastian-noel]

looks good! fixed a few things to bring this in line with the rest of the site:

• Fixed heading misuse — the card used <h1>/<h4>/<h3> purely for visual weight; switched to <p> to match TeamCard's pattern and avoid breaking the page's heading hierarchy
• Added missing target="_blank" rel="noopener noreferrer" on the external challenge link
• Swapped text-gray-400 for the text-text-secondary design token
• Replaced the 📆 emoji with a FaRegCalendarAlt icon (react-icons, same as the hero section)
• Lightened the deadline date color (text-accent → text-accent-light) for better readability on the dark card background, and dropped the border on the month pill
• 2-space indentation, string[] over Array, minor formatting cleanup