fix: update offerGiverDid to use credentialSubject.offeredBy

The offerGiverDid function was looking for offeredBy at the root level of the
OfferVerifiableCredential, but it was moved to credentialSubject in our interface
changes. This fix updates the function to look in the correct location while
maintaining the same fallback behavior of using the issuer if offeredBy is not
available.

- Update path from claim.offeredBy to claim.credentialSubject.offeredBy
- Remove unnecessary string type cast
- Keep issuer fallback behavior unchanged

src/libs/util.ts

@@ -389,10 +389,10 @@ export function offerGiverDid(
   let giver;
   const claim = veriClaim.claim as OfferVerifiableCredential;
   if (
-    claim.offeredBy?.identifier &&
-    !serverUtil.isHiddenDid(claim.offeredBy.identifier as string)
+    claim.credentialSubject.offeredBy?.identifier &&
+    !serverUtil.isHiddenDid(claim.credentialSubject.offeredBy.identifier)
   ) {
-    giver = claim.offeredBy.identifier;
+    giver = claim.credentialSubject.offeredBy.identifier;
   } else if (veriClaim.issuer && !serverUtil.isHiddenDid(veriClaim.issuer)) {
     giver = veriClaim.issuer;
   }