chore: review eip-7688 branch

[twoeths]

Description

• more progressive ssz utils to reuse nodes, this improves:
  • gloas fork transition to migrate basic list
  • progressParticipationFlagUpdates, which happens at epoch transition
• also do not check deposit length as found in feat: implement EIP 7688 #9390 (comment)

AI Assistance Disclosure

• created with the help of Claude

[gemini-code-assist]

Code Review

This pull request optimizes state transitions and upgrades to the Gloas fork by introducing efficient progressive list migrations and zero-filled node initializations, significantly reducing re-merkleization overhead. Specifically, it updates participation flag updates to use pre-computed zero nodes and refactors state upgrades to reuse existing basic and composite list nodes. The review feedback correctly identifies TypeScript compilation errors in upgradeStateToGloas.ts where fuluList.node (typed as Node) is accessed via .left without being cast to BranchNode. Implementing the suggested casts and importing BranchNode will resolve these compilation issues.

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[twoeths]

re-reviewed myself, merging to the eip-7688 branch now