src(lucid): add EIP-8184 LUCID encrypted mempool as unscheduled fork

[jflo]

Implements EIP-8184 (LUCID Encrypted Mempool) as a new unscheduled fork src/ethereum/forks/lucid/ (Unscheduled, order_index=4) built on top of Amsterdam (which includes FOCIL).

What's included

New fork — src/ethereum/forks/lucid/

• SealedTicketTransaction (type 0x05): outer bidding envelope with ChaCha20-Poly1305 encrypted payload, commitment hashes, and ToB fee
• process_sealed_tickets(): top-of-block execution of decrypted tickets in commitment order (descending ToB fee, then gas limit, then index)
• SLOTNUM opcode (0x4B): returns the slot number of the block in which the sealed ticket's commitment was included; 0 for ordinary transactions
• validate_sealed_transaction_context(): verifies ciphertext hash, key commitment, reveal commitment (SSZ hash_tree_root), and plaintext gas/fee constraints

Shared crypto — src/ethereum/crypto/

• chacha20poly1305.py: ChaCha20-Poly1305 AEAD decrypt wrapper
• ssz.py: SSZ hash_tree_root for RevealCommitmentPreimage

t8n support — src/ethereum_spec_tools/evm_tools/t8n/

• Accepts sealedTransactionContexts in the env JSON input
• Executes sealed tickets before the regular transaction list

Running the tests

# Blockchain tests (SLOTNUM opcode) fill tests/unscheduled/eip8184_lucid/test_lucid.py --fork Lucid

# Unit tests (fee calculation, ordering, context validation) pytest tests/unscheduled/eip8184_lucid/test_lucid_unit.py

The test_lucid_unit.py file uses plain pytest (not fill) and is excluded from fill collection automatically by conftest.py.

🗒️ Description

🔗 Related Issues or PRs

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✅ Checklist

• All: Ran fast static checks to avoid unnecessary CI fails, see also Code Standards and Enabling Pre-commit Checks:

  just static

• All: PR title adheres to the repo standard - it will be used as the squash commit message and should start type(scope):.
• All: Considered updating the online docs in the ./docs/ directory.
• All: Set appropriate labels for the changes (only maintainers can apply labels).
• Tests: Ran mkdocs serve locally and verified the auto-generated docs for new tests in the Test Case Reference are correctly formatted.
• Tests: For PRs implementing a missed test case, update the post-mortem document to add an entry the list.
• Ported Tests: All converted JSON/YML tests from ethereum/tests or tests/static have been assigned @ported_from marker.

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