feat(client): support custom claims in PrivateKeyJwtProvider#1875

pcarleton merged 2 commits intomodelcontextprotocol:mainmodelcontextprotocol/typescript-sdk:mainfrom

JosephDoUrden:feat/private-key-jwt-custom-claimsJosephDoUrden/typescript-sdk:feat/private-key-jwt-custom-claimsCopy head branch name to clipboard