chore(Distributor): Dead code — pre-Pectra permissionless distributeFor path

[sailorpepe]

Summary

The Pectra11 hard fork (timestamp 1756915200, Sept 3 2025) made distributeFor(uint64, uint64, bytes, bytes32[], bytes32[]) permanently unreachable. The function contains a guard that always reverts post-Pectra. Only the system-call distributeFor(bytes pubkey) path remains active.

Dead code inventory

Item	Location
distributeFor(uint64, uint64, bytes, bytes32[], bytes32[])	Distributor.sol
PECTRA11_HARD_FORK_TIMESTAMP	Distributor.sol
MANAGER_ROLE	Distributor.sol
setZeroValidatorPubkeyGIndex / setProposerIndexGIndex overrides	Distributor.sol
5-arg distributeFor declaration	IDistributor.sol
Distributor MANAGER_ROLE grants	3_DeployPoL.s.sol, 4_TransferPOLOwnership.s.sol

Constraints

• BeaconRootsHelper.sol must remain in the inheritance chain — Distributor_V0.sol depends on it, and removing it would break UUPS proxy storage layout compatibility.
• The base BeaconRootsHelper setters (setZeroValidatorPubkeyGIndex, setProposerIndexGIndex) are public virtual with no access control. Removing the onlyRole(MANAGER_ROLE) overrides from Distributor exposes them. They should be locked with revert overrides.

Proposal

Remove the dead code, migrate all test coverage to the system-call path, and add revert overrides for the unprotected base setters. I have a PR ready.