feat : improve password validation

[smitdodiya]

Issue:
Fixes [Bug]: User sees confusing error message when entering an unsupported password (#53 / #91)

Problem:
Currently, when users enter an invalid password - Kratos sometimes shows a misleading errors.

What this PR does :
Replaces harsh / confusing system errors with clear and friendly validation messages

Guides users toward the expected password format:

• Minimum 8 characters
• Alphanumeric
• At least one special character

Expected Result:
Users clearly understand why their password is invalid and how to fix it, without seeing alarming or misleading messages.

Notes:
No backend/Kratos behavior is modified
Changes are limited to frontend validation and error presentation