Implement retrieving PTC duties + PayloadAttestationPool skeleton

[StefanBratanov]

PR Description

Add the necessary methods to implement for the Payload timeliness attestation duty

This PR implements getPtcDuties as a start and adds PayloadAttestationPool which is to be implemented in future PRs. Also changed the BlockOperationSelectorFactory to use the pool as well as handle gossip for payload attestations to be redirected to the pool. Also add publishing of the payload attestation message when added locally.

Fixed Issue(s)

related to #10041

Documentation

• I thought about documentation and added the doc-change-required label to this PR if updates are required.

Changelog

• I thought about adding a changelog entry, and added one if I deemed necessary.

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Note

Implements PTC duties retrieval and scaffolds payload attestation pooling with gossip integration across block production, APIs, spec utilities, networking, metrics, and tests.

• Validator/API:
  • Add getPtcDuties with state/epoch validation and new JSON types (PtcDuties, PtcDuty).
  • Stub createPayloadAttestationData and sendPayloadAttestationMessages endpoints; extend metrics labels.
  • Minor refactor: proposer duties helper.
• Spec/Logic:
  • Add PTC assignment helpers: Spec.getPtcAssignment, getValidatorIndexToPtcAssignmentMap; base stubs in ValidatorsUtil, Gloas impl in ValidatorsUtilGloas.
  • Use RestApiConstants.DEPENDENT_ROOT in attester duties JSON.
• Gossip/P2P:
  • Add PayloadAttestationMessage publish path in Eth2P2PNetwork, ActiveEth2P2PNetwork, and GossipForkManager.
• State Transition / Pools:
  • Introduce PayloadAttestationPool (NOOP + AggregatingPayloadAttestationPool) and PayloadAttestationMessageValidator.
  • Wire pool in BeaconChainController (init, gossip processing, local publish).
• Block Production:
  • BlockOperationSelectorFactory now sources payload attestations from the pool (tests updated; BeaconBlockBodyLists.createPayloadAttestations).
• Tests:
  • Update factories and assertions across milestones to include payload attestations and new API (getPtcDuties).

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[cursor]

Bug: Epoch Mismatch in Duty Calculation

The getPtcDuties method retrieves BeaconState from the previous epoch, but then uses this state to calculate duties and the dependent root for the requested epoch. This mismatch can result in incorrect PTC assignments and an improperly selected dependent root.