feat(auth): add password strength meter and validation to signup form

[hrx01-dev]

Description

Overview

Improve account security and user experience by implementing password strength analysis in the signup flow. Users should receive real-time feedback on password quality and be prevented from creating accounts with weak passwords.

Current Behavior

• Users can enter any password during signup.
• No visual indication of password strength is provided.
• Weak passwords may be accepted without warning.

Expected Behavior

• Password strength is evaluated as the user types.
• A visual strength indicator (Weak / Medium / Strong) is displayed.
• Password requirements are shown with live validation.
• Signup is blocked if the password does not meet minimum security requirements.

Requirements

Password Strength Criteria

Evaluate password strength based on:

• Minimum 8 characters
• At least 1 uppercase letter
• At least 1 lowercase letter
• At least 1 number
• At least 1 special character

Strength Levels

Score | Label -- | -- 0-2 | Weak 3-4 | Medium 5 | Strong

UI Components

Strength Meter

• Display a progress bar beneath the password field.
• Update in real time as the user types.
• Show color-coded feedback:
  • Red = Weak
  • Yellow/Orange = Medium
  • Green = Strong

Requirements Checklist
Display live validation indicators:

✓ At least 8 characters
✓ Contains uppercase letter
✓ Contains lowercase letter
✗ Contains a number
✗ Contains a special character

Form Validation

• Prevent signup when password strength is classified as "Weak".
• Display a clear error message/toast explaining why submission was blocked.
• Ensure validation is enforced both visually and within form submission logic.

Acceptance Criteria

• Password strength updates in real time.
• Strength meter is visible and responsive.
• Password requirements checklist updates dynamically.
• Weak passwords cannot be submitted.
• Error message/toast appears when validation fails.
• Component is responsive across mobile and desktop devices.
• Existing signup functionality remains unaffected.
• Unit tests added for password strength calculation logic.

[krishnnag998-del]

/assign

[github-actions]

✅ Assigned @krishnnag998-del