fix: validation of signup passwords for the frontend

Description:

Fixed signup password validation flow to match backend validation rules before OTP request. Previously, weak passwords were accepted in frontend and rejected only during OTP verification, causing users to return to signup form after entering OTP. Now password validation happens before OTP is requested, preventing invalid passwords from entering OTP flow.

Type of Change:

• Bug Fix
• Feature Development

Testing:

• ✅ Tested on desktop
• ⬜ Tested on mobile
• ✅ Tested in different browsers

Screenshots (if applicable):

AI-assisted implementation used for:

• Backend/frontend validation audit
• Password validation sync logic
• OTP flow correction
• Validation UX improvements

Please attach a short video explaining:

• What was broken
• Root cause
• Files changed
• Validation flow fix
• Testing completed

Link to Code Walkthrough:

Add walkthrough/demo link here.

Checklist:

• ✅ Code follows project style guidelines
• ✅ Self-review completed
• ✅ No console errors
• ✅ TypeScript types are correct