Strategy 패턴 적용

[yjeong-k]

PR Title: Strategy 패턴 적용

Related Issue(s):

PR Description:

EmailVerificationViewModel에 strategy 패턴을 적용하였습니다
자세한 사항은 제출할 design pattern document 참고해주시면 감사하겠습니다

Changes Included:

• Added new feature(s)
• Fixed identified bug(s)
• Updated relevant documentation

Notes for Reviewer:

Any specific instructions or points to be considered by the
reviewer.

Reviewer Checklist:

• Code is written in clean, maintainable, and idiomatic form.
• Automated test coverage is adequate.
• All existing tests pass.
• Manual testing has been performed to ensure the PR works as expected.
• Code review comments have been addressed or clarified.

Additional Comments:

Add any other comments or information that might be useful for the
review process.