fix: prevent sybil bypass via delete then re claim and fix status code mismatch

[Sertug17]

There was a bug in the airdrop claim flow someone could delete their claim via delete-airdrop, then re-claim with a different wallet using the same social account. The delete was removing the verification token entirely, so the re verification check had nothing to find.

Added a DeletedToken model. When someone deletes their claim, the token gets saved there instead of being thrown away. On re verification, we check both the active records and the deleted token table.

Also fixed a smaller issue: the frontend was checking for HTTP 400 but the backend returns 412 for "traits not satisfied". Dead code basically that error path never worked. Changed the frontend check to 412.

[vercel]

@Sertug17 is attempting to deploy a commit to the Coinbase Team on Vercel.

A member of the Team first needs to authorize it.

[Sertug17]

Would appreciate a review on this when either of you gets a chance. Fixes a sybil bypass in the claim flow (delete + re-claim reuses the same verification token) and corrects a status code mismatch between frontend and backend for the traits-not-satisfied path.

@patnir @kushagras481