fix: add custom terminal-themed form validation UI

[Bluerock-crypto]

What does this PR do?

Fixes #41

Changes made:

• Added novalidate to the form to disable default browser validation popups
• Added custom error message spans below each input field
• Added CSS styling for terminal-themed error messages in main.css
• Added JavaScript validation inside the existing submit handler to show custom errors before form processing

How to test:

1. Go to the registration page
2. Click "Register Now" without filling any fields
3. Custom terminal-styled error messages appear below each field

[jagdish-15]

I've left code suggestions for the shake animation and for automatically clearing validation errors once a field becomes valid again.

Feel free to commit them directly!

[Bluerock-crypto]

Hi @jagdish-15 I've committed both suggestions. Please review when you get a chance. Thank you for the feedback!

[jagdish-15]

/format

[github-actions]

I have successfully run Prettier and pushed the formatting fixes to this PR.

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