Fix join add icpc

[condyl]

Changes 🛠

What does this PR do?

This PR updates the navigation and links page with the following changes:

1. Updates mobile navigation: Changes the "Join" button in the mobile navigation to redirect to /links instead of /signup
2. Adds ICPC registration button: Adds a new prominent button on the links page for ICPC Qualifiers Registration that links to the event page
3. Adds ICPC icon: Includes a new ICPC logo icon (icpc.png) in the assets for the registration button

The changes improve user navigation by directing users to the centralized links page and provide easy access to ICPC registration.

Screenshots 🖼

Before

• Mobile "Join" button redirected to /signup
• Links page did not have ICPC registration option

After

• Mobile "Join" button now redirects to /links
• Links page includes a new ICPC Qualifiers Registration button with icon at the top of the links list

Any new npm dependencies?

NO

Testing 🧪

Changes from the latest PR are deployed to https://brockcsc-pr.web.app once the checks are complete. Can use this for testing.

Any other info needed for testing?

Test the following:

1. On mobile view, verify the "Join" button in the navigation redirects to /links
2. On the links page, verify the new ICPC Qualifiers Registration button appears at the top with the ICPC icon
3. Verify the ICPC button correctly redirects to the event page: https://brockcsc.ca/events/-Oa1cJ_JZxT1FeYCp3uy

NO

[AlaqmarG]

Very bad PR make better lolz