Update Contest on Explore Page

[devin-ai-integration]

Link to Issue
Closes: #10320

Description of Changes

• Rename "/communities" link to "/explore"
• Update header to show only "explore" instead of "explore communities"
• Implement new contest sorting logic:
  • Active contests appear first
  • Active contests sorted by closest end_date (ending soonest)
  • For same end_date, sort by prize amount (descending)
  • Inactive contests sorted by most recent end date (descending)

Test Plan

1. Navigate to /explore (previously /communities)
2. Verify header shows only "Explore"
3. Test contest sorting:
   • Create multiple contests with different end dates and prize amounts
   • Verify active contests appear first
   • Verify active contests are sorted by end date (soonest first)
   • Verify contests with same end date are sorted by prize amount
   • Verify inactive contests are sorted by most recent end date

Deployment Plan
Standard deployment process - no special steps required.

Other Considerations
N/A

Link to Devin run: https://app.devin.ai/sessions/d0d961146c4b443cbbc55ed9a3828928

[devin-ai-integration]

🤖 Devin AI Engineer

I'll be helping with this pull request! Here's what you should know:

✅ I will automatically:

• Address comments on this PR
• Look at CI failures and help fix them

⚙️ Control Options:

• Disable automatic comment and CI monitoring

Add "(aside)" to your comment to have me ignore it.