Security: Add CSRF protection to API routes

[LaGodxy]

Summary

The API routes lack CSRF protection.

Implementation

• CSRF token generation on session start
• Token validation middleware
• SameSite cookie attribute
• Origin header validation
• Double-submit cookie pattern

[nafsonig]

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

Hello maintainer, please let me work on this issue as soon as possible

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[drips-wave]

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

🧑‍💻 @nafsonig: 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 @nafsonig as part of the Stellar Wave Program's 4th Wave 🥳

😎 @nafsonig: 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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