feat: added validation for register page with proper error messages

[viral-shingadia]

PR Title: Improve password validation message to be more user-friendly

Fixes Issue

Closes #53

Changes Proposed

• Updated password validation logic on the registration form.
• Added a single, clear error message for all password complexity failures.
• Replaced unclear or misleading messages such as:
  • “The password has been found in data breaches and must no longer be used.”
  • “The password must be at least 8 characters long, but got 6.”
• Ensured frontend validation matches expected behavior:
  • Password must be minimum 8 characters
  • Must contain one uppercase
  • Must contain one lowercase
  • Must contain one number
  • Must contain one special character

Check List

• My code follows the code style of this project.
• The title of my pull request is a short description of the requested changes.

Note to Reviewers

This update ensures that password validation is clear, friendly, and consistent.
A unified message is shown to users:

Password must contain 8 characters, one uppercase, one lowercase, one number, and one special character.

This resolves user confusion caused by previous backend error messages.