feat(components): add client-side validation to contact form

[shreyashap]

Description

This pull request implements client-side validation for the "Send Us Message" form on the landing page. The changes ensure that the form checks for required fields and validates the format of the email and phone number before submission. Specific error messages are displayed when fields are invalid, and the error is cleared when the user updates the field.

Changes Made

• Added validation for fullName, email, phone, and message fields.
• Error messages are displayed below the respective fields when validation fails.
• Form submission is prevented if any field is invalid.
• Error messages are cleared dynamically when the user modifies the value in the input fields.

How to Test

1. Navigate to the "Send Us Message" form on the landing page.
2. Submit the form without filling out any fields or with invalid data.
3. Verify that the appropriate error messages appear.
4. Update each field and ensure that errors are cleared when the field is corrected.
5. Submit the form with valid data and check that it successfully sends the message.

Related Issues

Closes #188