Update parsed fields on email receiving API

[toofishes]

• Add message ID - Matches Node SDK PR feat: add message_id to inbound email response resend-node#702
• object is "email", not "inbound - matches Node SDK PR fix: inbound entity should still be called email resend-node#721
• Add raw download URL and expiration time to ReceivedEmail struct, documented here: https://resend.com/docs/api-reference/emails/retrieve-received-email

---

Summary by cubic

Updated the receiving API models to add message_id and raw download info, and changed the object value to "email" to match the Node SDK and docs. Tests updated to cover the new fields.

• New Features

  • ReceivedEmail: added message_id and raw (download_url, expires_at).
  • ListReceivedEmail: added message_id.
  • Object for received emails is now "email" (was "inbound").

• Migration

  • Update any logic that checks object == "inbound" to object == "email".

^{Written for commit 93c6e01. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 2 files

[drish]

thanks for your contribution @toofishes