Add password strength evaluation script

[Satwikdas122]

Motivation

• Provide a small, standalone tool to evaluate password strength by analyzing length, character variety, repeated characters, sequential patterns, and common passwords, and to give actionable suggestions.
• Make the tool available as a simple CLI script and document it in the repository README.md so it can be easily discovered and used.

Description

• Add password_strength.py, a CLI tool that exposes evaluate_password and returns a StrengthResult dataclass with a numeric score, level, and suggestions.
• Implement scoring heuristics in _classify including length scoring, character-class variety, unique-character ratio, common-password checks, and sequential-character detection via _has_sequence.
• Provide human-friendly strength levels (Very Weak → Very Strong) and build a small interactive main() to print results and suggestions.
• Update README.md to mention the new password-strength tool and point to password_strength.py.

Testing

• No automated tests were run for this change.

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Codex Task