Align sponsor idempotency across Developer SDKs

[edo-chan]

Summary

• remove unsupported sponsor metadata from the TypeScript and Python public contracts
• retain optional idempotency keys and forward the same wire field in both SDKs
• extend the Python local E2E to retry a real sponsored Surfpool transaction and verify no balance change repeats
• add a minor changeset for @swig-wallet/developer-sdk

Backend enforcement is merged in swig-dev-portal#674.

Verification

• TypeScript: 79 tests, typecheck, lint, package build
• Python: 19 tests, Ruff, Mypy, sdist and wheel build
• local Python E2E against Tilt + Surfpool + paymaster + Redis: status: ok, paymaster_idempotency_replayed: true
• live paymaster logs confirmed the second call replayed the original request ID
• git diff --check