feat: update homepage events to show BMT 2025 tournaments

[devin-ai-integration]

feat: update homepage events to show BMT 2025 tournaments

Summary

Updated the homepage event listing to focus on high school BMT 2025 tournaments instead of middle school BmMT tournaments. The changes reduce the total number of featured events from 4 to 3:

Removed:

• Berkeley mini Math Tournament 2025 (April 12, 2025) - middle school in-person tournament
• BmMT 2025 Online (June 7, 2025) - middle school online tournament

Added/Updated:

• BMT 2025 Online (December 6, 2025) - high school online tournament
• BMT 2025 China (November 29-30, 2025) - updated from "BmMT" to "BMT" with new date

The homepage now displays: BMT 2025 (in-person), BMT 2025 Online, and BMT 2025 China.

Review & Testing Checklist for Human

• Verify ASDAN external URL: The China tournament URL was changed from https://www.seedasdan.asia/en/bmmt-en/ to https://www.seedasdan.asia/en/bmt-en/. Please click this link to confirm it's not a 404 - this is the highest risk item in the PR.
• Confirm BMT China date with ASDAN: The date was set to November 29-30, 2025 (weekend after Thanksgiving) based on user input. Please verify this date is correct with ASDAN/tournament organizers.
• Visual layout verification: Test the homepage appearance with 3 events instead of 4 across different screen sizes (mobile, tablet, desktop). The grid layout changed from (col-span-6, col-span-4, col-span-2, col-span-6) to (col-span-6, col-span-4, col-span-2).
• Strategic alignment: Confirm this change aligns with Berkeley MT's 2025 communication strategy - shifting from promoting middle school tournaments to high school tournament variants.
• Verify BMT 2025 Online event page: Click through to /events/bmt-2025-online/ to ensure the page exists and matches the December 6, 2025 date shown on the homepage.

Test Plan

1. Visit the deployed preview of the homepage
2. Verify all three event cards render correctly and have balanced vertical heights
3. Click each event link to ensure they work (especially the external BMT China link)
4. Test responsive behavior on mobile/tablet to ensure the grid adapts properly

Notes

• BMT 2025 Online event page already exists at /events/bmt-2025-online/ with December 6, 2025 date
• Description lengths were adjusted to balance vertical heights per user request
• Requested by Oliver Ni (oliver.ni@gmail.com) via @oliver-ni
• Link to Devin run: https://app.devin.ai/sessions/4d349080061e46268645ef9de1ba2267

[devin-ai-integration]

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