fix: handle genesis block in gloas fork choice and genesis state init

[barnabasbusa]

Summary

• Fork choice fix: Handle genesis block's all-zeros parentRoot in getParentPayloadStatus() — returns PayloadStatus.FULL instead of throwing PROTO_ARRAY_ERROR_UNKNOWN_PARENT_BLOCK. This fixes the mainnet preset crash at block production time.
• Genesis init fix: Guard latestExecutionPayloadHeader assignments in initializeBeaconStateFromEth1() with fork < ForkSeq.gloas since this field was removed in gloas (EIP-7732), replaced by latestExecutionPayloadBid.

Note on minimal preset SSZ crash

The minimal preset crash (First offset must equal to fixedEnd 109509 != 11589) is a genesis generator issue, not Lodestar. The difference of 97920 bytes exactly matches ptcWindow size with mainnet PTC_SIZE=512 vs minimal PTC_SIZE=2 — the genesis generator (ethpandaops/ethereum-genesis-generator:gloas-genesis) appears to use mainnet's PTC_SIZE when generating minimal preset states.

Test plan

• All fork-choice unit tests pass (104/104)
• Beacon-node fork choice tests pass
• Type check passes
• Lint passes
• Test with Kurtosis devnet using mainnet preset

🤖 Generated with Claude Code

[gemini-code-assist]

Code Review

This pull request introduces a check in the fork-choice logic to treat the genesis block as a full payload when the parent root is a zero hash. Additionally, it updates the genesis state initialization to conditionally set the latest execution payload header only for forks prior to gloas. A review comment identifies a type safety improvement opportunity in the genesis utility, noting that the executionPayloadHeader parameter is missing the Fulu-specific header type in its union definition, which leads to unnecessary casting.

[nflaig]

this looks good, still doing a quick sanity check, I don't think I ever tested gloas from genesis before

we also need to bring this to unstable branch, I can look into that more later

[nflaig]

still seeing fork choice erros after genesis

Apr-01 17:50:52.013[chain]           error: Failed to run prepareForNextSlot nextEpoch=1, isEpochTransition=false, prepareSlot=22, code=FORKCHOICE_ERROR_MISSING_PROTO_ARRAY_BLOCK, root=0x8fd75b4c4ad764977c656e3466346e7a82b9601833f0e93ef6ec8bd69787b19a
Error: FORKCHOICE_ERROR_MISSING_PROTO_ARRAY_BLOCK
    at ForkChoice.getJustifiedBlock (file:///usr/app/packages/fork-choice/src/forkChoice/forkChoice.ts:1143:13)
    at getSafeExecutionBlockHash (file:///usr/app/packages/fork-choice/src/forkChoice/safeBlocks.ts:26:21)
    at Clock.prepareForNextSlot (file:///usr/app/packages/beacon-node/src/chain/prepareNextSlot.ts:165:33)

will merge this anyways, can fix that as part of the other wip