(NFT) put minted NFT tracking in Clip model

[Eniola3321]

Description:
Track which clips have been minted and their on-chain mint address.
Acceptance Criteria:

Add fields to Clip: mintAddress String?, mintedAt DateTime?, nftStatus String? ("none", "minting", "minted", "failed")
Update on successful mint
Prevent double minting

[drips-wave]

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

🧑‍💻 @Adedayo-Data: 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.

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[drips-wave]

This issue has been marked as completed by a Drips Wave moderator for @Adedayo-Data as part of the Stellar Wave Program's 4th Wave 🥳

Moderator's reason: Issue was resolved, and merged in PR: #129

😎 @Adedayo-Data: 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.

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ℹ️ Note: This issue was marked complete via moderation. Points were issued even though the GitHub issue remains open.