feat: Add Success Message and Form Validations to Appointment Form

[akshay0611]

Summary: This PR adds a success message and form validations to the appointment form to improve user experience. The changes aim to ensure valid inputs and provide feedback upon successful submission.

Changes Made:

• Added HTML5 validation attributes (pattern, required, min) to form fields.
• Included JavaScript to validate inputs and display alerts for invalid fields.
• Added a success message that appears after form submission.
• Ensured alignment with existing CSS styles and framework conventions.

Testing:

• Verified responsiveness across different screen sizes.
• Tested form validations to ensure invalid inputs trigger appropriate alerts.
• Ensured proper rendering of the success message and form reset functionality.

Related Issue: Closes #20