core: version and broadcast payload attestation message

[KaloyanTanev]

Refactor core.SignedPayloadAttestationMessage into core.VersionedPayloadAttestationMessage wrapping eth2spec.VersionedPayloadAttestationMessage, mirroring #4663 on the signed side and following the VersionedAttestation pattern. The parsig wire format (SSZ/JSON) now carries the fork version, and the validatorapi submit handler uses the validating constructor instead of a hardcoded gloas check.

On top of that, add DutyPayloadAttestation to the broadcaster: unwrap the signed set and submit via SubmitPayloadAttestationMessages, with no version fabrication anywhere.

category: feature
ticket: #4324

[Copilot]

Pull request overview

This PR refactors payload attestation messages on the “signed/parsig” side to be fork-versioned, aligning them with the existing “versioned data” patterns (and mirroring the earlier VersionedPayloadAttestationData work). It updates wire formats (SSZ/JSON) and the validator API submit path to use validating constructors rather than hardcoded Gloas checks, enabling fork-version-aware handling end-to-end.

Changes:

• Introduces core.VersionedPayloadAttestationMessage wrapping eth2spec.VersionedPayloadAttestationMessage, including SSZ + JSON envelope encoding with the fork version.
• Updates validatorapi payload attestation message submission to use the validating constructor and versioned accessors (Data(), ValidatorIndex()).
• Updates fuzz/random generators, proto decoding, and golden/SSZ tests to cover the new versioned message format.

Reviewed changes

Copilot reviewed 14 out of 15 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
testutil/random.go	Adds a random generator for eth2spec.VersionedPayloadAttestationMessage to support tests/helpers.
testutil/fuzz.go	Adds fuzzing support for core.VersionedPayloadAttestationMessage (fixed version set to Gloas).
core/validatorapi/validatorapi.go	Replaces hardcoded Gloas checks with NewPartialVersionedPayloadAttestationMessage + versioned accessors.
core/validatorapi/validatorapi_test.go	Updates expected parsig objects to use the new versioned constructor.
core/ssz.go	Implements SSZ marshal/unmarshal for VersionedPayloadAttestationMessage using the versioned envelope.
core/ssz_test.go	Updates SSZ tests to validate the new versioned envelope bytes and round-trip behavior.
core/signeddata.go	Adds VersionedPayloadAttestationMessage type, constructor/partial constructor, MessageRoot/signature plumbing, and JSON wrapper format.
core/serialise_test.go	Switches JSON golden serialization coverage to the new versioned type.
core/proto.go	Updates parsig proto decoding for DutyPayloadAttestation to unmarshal VersionedPayloadAttestationMessage.
core/eth2signeddata.go	Updates Eth2SignedData implementation to use VersionedPayloadAttestationMessage for domain/epoch.
core/eth2signeddata_test.go	Updates Eth2SignedData verification test to build a valid versioned payload attestation message.
core/testdata/TestSSZSerialisation_SignedPayloadAttestationMessage.ssz.golden	Removes obsolete golden for the removed signed-only payload attestation message format.
core/testdata/TestJSONSerialisation_SignedPayloadAttestationMessage.json.golden	Removes obsolete golden for the removed signed-only JSON payload attestation message format.
core/testdata/TestJSONSerialisation_VersionedPayloadAttestationMessage.json.golden	Adds new JSON golden for the versioned message wrapper format.

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[Copilot]

Pull request overview

Copilot reviewed 16 out of 17 changed files in this pull request and generated 1 comment.

[codecov]

Codecov Report

❌ Patch coverage is 61.22449% with 57 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (gloas@6e58d4c). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
core/signeddata.go	53.94%	27 Missing and 8 partials ⚠️
core/ssz.go	68.75%	6 Missing and 4 partials ⚠️
core/validatorapi/validatorapi.go	53.84%	3 Missing and 3 partials ⚠️
core/bcast/bcast.go	78.94%	2 Missing and 2 partials ⚠️
core/eth2signeddata.go	66.66%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##             gloas    #4668   +/-   ##
========================================
  Coverage         ?   58.78%           
========================================
  Files            ?      246           
  Lines            ?    34746           
  Branches         ?        0           
========================================
  Hits             ?    20427           
  Misses           ?    11778           
  Partials         ?     2541           

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