Implement transaction receipt generation

[mw2000]

Summary

Generate transaction receipts after execution. Receipts contain the status, cumulative gas used, logs, and bloom filter — required for block validation and event querying.

Specification

Receipt struct:

%Receipt{
  status: 0 | 1,              # 0 = failure, 1 = success
  cumulative_gas_used: non_neg_integer(),
  logs: [log_entry()],
  logs_bloom: <<_::2048>>      # 256-byte bloom filter
}

Encoding

• Legacy tx receipts: RLP.encode([status, cumulative_gas, bloom, logs])
• Typed tx receipts: tx_type ++ RLP.encode([status, cumulative_gas, bloom, logs])

Implementation Guide

1. Create lib/eevm/receipt.ex with the Receipt struct
2. Generate receipt from TransactionResult — status from execution result, logs from MachineState, bloom via EEVM.Bloom
3. Add encode/1 for RLP encoding (both legacy and typed)
4. Cumulative gas is the sum of gas used by all txs in the block up to and including this one — tracked at the block level
5. Tests: receipt from successful tx, receipt from reverted tx, receipt encoding, bloom filter matches logs

Acceptance Criteria

• Receipt struct with all required fields
• Status correctly reflects execution success/failure
• Logs bloom computed from receipt logs
• RLP encoding for legacy and typed receipts
• Tests pass

Reference

• Yellow Paper §4.3.1 (Receipt)
• EIP-2718 (Typed receipts)