[BE-11] Implement auth login endpoint (POST /auth/login)

[yusuftomilola]

Overview

Implement the login endpoint that validates credentials and returns JWT tokens inside backend/contrib/.

Location

All work must be inside backend/contrib/src/auth/.

Acceptance Criteria

• POST /auth/login endpoint implemented
• LoginDto with email and password fields
• Password verified using bcrypt.compare
• Returns { accessToken, refreshToken, user } on success
• Throws UnauthorizedException (401) on invalid credentials
• Hashed refresh token stored in DB via UsersService

[tolulopedd26]

@tolulopedd26 has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

can i work on this?

ℹ️ Repo Maintainers: To accept this application, review their application or assign @tolulopedd26 to this issue.

[drips-wave]

Congratulations, @tolulopedd26! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on April 29, 2026.

🧑‍💻 @tolulopedd26: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

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[drips-wave]

This issue has been completed by @tolulopedd26 as part of the Stellar Wave Program's 4th Wave 🥳

😎 @tolulopedd26: You earned 200 Points for completing this issue! After the current Wave ends, you'll be eligible for a percentage of the Wave's reward pool based on the percentage of total points you've earned. Learn more here. You can also Leave a review to share your experience working on this issue.

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