Feat: Adjust log types

[vineetpant]

Introduction

EIP-7745 introduces a new log indexing mechanism that replaces traditional bloom filters with a more efficient
LogIndexSummary structure. This requires:

• SSZ serialization of log data for hash tree root calculations
• Fixed-size List[T, N] for topics (max 4 topics per log)

Description

This PR updates the Log type in eth/common/receipts.nim to use SSZ List[Hash32, 4] for topics instead of seq[Hash32], enabling proper SSZ serialization required for EIP-7745 (Log Value Index).

Details

1. Log Type Update (eth/common/receipts.nim)

• Changed topics field from seq[Hash32] to List[Hash32, 4]
• Maintains backward compatibility with RLP encoding
• Enables SSZ serialization for LogIndex functionality

2. SSZ Serialization Support (eth/common/ssz_utils.nim)

• Added SSZ serialization helpers for List[Hash32, 4]
• Ensures proper encoding/decoding of log topics

3. RLP Writer Fixes (eth/rlp/writer.nim)

• Fixed IndexDefect crash when encoding SSZ List[T, N] types

4. Dependency Update (eth.nimble)

• Updated ssz_serialization dependency to support List[T, N] types

Breaking Changes

None - This change is backward compatible:

References

• Pureth Implementation guide: https://pureth.guide/implementations-7745/
• EIP-7745 Spec: https://eips.ethereum.org/EIPS/eip-7745