Add linear algebra competition to events

[msaroufim]

Summary

• add the open Linear Algebra Kernels For The Age Of Research competition to the Events page
• link the Events card to the existing linear algebra news/blog post
• allow competition cards without an end date so no due date is displayed yet

Validation

• git diff --check
• npm ci
• npm run build

Note: npm ci reported existing npm audit findings, but dependency installation and the production build completed successfully.