execution/types, stagedsync: EIP-7928 phantom-read early reject

[yperbasis]

Summary

Implements the EIP-7928 Security-Considerations mitigation against a malicious proposer declaring phantom storage_reads. The existing ValidateMaxItems only checks the overall BAL size bound post-execution — after the client has already paid the I/O cost the mitigation is meant to avoid. This PR adds the per-tx gas-feasibility budget check:

G_remaining >= R_remaining * BalItemCost   (BalItemCost = 2000)

where R_remaining is the number of declared storage_reads not yet observed in actual execution.

Changes

• execution/types/block_access_list.go
  • BlockAccessList.CountDeclaredReads() int — R_declared.
  • DeclaredReadTracker (NewDeclaredReadTracker(bal), ObserveRead(addr, slot), Remaining()) — idempotent so safe under the parallel executor's speculative re-execution.
  • EarlyRejectCheck(blockGasLimit, gasUsed, remainingDeclaredReads) error.
• execution/stagedsync/exec3_parallel.go
  • blockExecutor gains blockGasLimit (captured from the fresh gasPool) and declaredReadTracker (built from the declared accessList already plumbed in).
  • New gasUsedSoFar() helper computes blockGasLimit - min(regular, state) so the check is conservative across both EIP-8037 dimensions.
  • After each tx validates and consumes its gas in nextResult, the finalized read set is scanned for StoragePath reads, attributed via ObserveRead, and EarlyRejectCheck runs. Failure routes through the existing invalidBlockResult path as ErrInvalidBlock.

Test plan

• go test ./execution/types/ — new unit tests cover counting, draining, idempotency, undeclared-slot no-ops, empty BAL, gas boundary, and gas-accounting bug.
• go test ./execution/stagedsync/ -short — no regressions.
• make lint clean (twice).
• make erigon integration — builds.
• Sequential path (exec3_serial.go) — not yet wired; same hook applies, deferred to keep this PR focused. Will follow up.
• End-to-end test driving a phantom-read block through the parallel executor — blockExecutor setup is heavy; the pure-logic unit tests cover the check, and the integration site is ~10 lines.

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