Hide broken Discord and Email link and update layout classes

[jnakaigen]

Description

This PR fixes a layout alignment issue in the "Contact Us" section and temporarily hides incomplete contact options to improve user experience.

Changes made:

1. Hidden Broken Links: Commented out the "Discord" and "Email" cards in the contactList array. These items had empty URL strings (''), which caused the page to reload or jump when clicked.
2. Improved Layout: Switched the container class from a fixed 4-column grid (grid lg:grid-cols-4) to a flexible centered layout (flex flex-wrap justify-center). This ensures the remaining two cards (Zulip and Github) are perfectly centered on the screen, rather than being stuck on the left side.

Checklist

• Ran npx prettier --write . (for formatting)
• Ran gofmt -w . (for Go backend)
• Ran npm test (for JS/TS testing)
• Added unit tests, if applicable
• Verified all tests pass
• Updated documentation, if needed

Additional Notes

The switch to flex-wrap is future-proof; if the Discord and Email links are uncommented later, the layout will automatically adjust to center all 4 items again.

Note to Maintainers: I commented out the Discord and Email sections because their URLs were missing. If you have the valid invite links, let me know and I can update the URLs file and uncomment these sections.

[github-actions]

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[its-me-abhishek]

This is not really required, closing until we find something else instead!