Add validation for registration page

[bakaydmytro]

First Name:

• Required field.
• Minimum of 2 characters, maximum of 50.
• Only letters allowed

Last Name:

• Required field.
• Minimum of 2 characters, maximum of 50.
• Only letters are allowed.

Email:

• Required field.
• Must follow a valid email format (e.g., name@example.com).

Age:

• Required field.
• Must be a positive integer.
• Range from 10 to 100

Password:

• Required field.
• Minimum of 8 characters.
• Must include at least one uppercase letter, one lowercase letter, one number, and one special character for security.

Password Confirmation:

• Required field.
• Must exactly match the password field.

[NataliaVoloshynska]

2 SP

[bakaydmytro]

@Sashlychok