Add PDP scheduling API boundary interfaces

[anjor]

Next after this:

1. Add a real schedule-level deal-type source (DB field or deterministic resolver rule), replacing test-only resolver behavior.
2. Implement PDPProofSetManager (ensure proof set + queue add-roots tx).
3. Implement PDPTransactionConfirmer (receipt polling + confirmation depth).
4. Wire runPDPSchedule to:
   • pick wallet/car batch,
   • ensure proof set,
   • queue tx,
   • wait for confirmation,
   • only then create/update PDP deal records.
5. Add persistence for on-chain workflow state (tx hash, confirmation status) so retries/restarts are safe.
6. Add integration tests for PDP sequencing and failure recovery.

Let me know if you would like me to include any of this in the same PR. @parkan