Complete Firehose mapping and parity for Cancun, Prague, and non-Arbitrum chains

[DenisCarriere]

Context

PR #1 is verified on Arbitrum Orbit. The sidecar currently emits the core block/receipt/trace fields needed there, but enabling it on Ethereum-family chains with newer transaction formats can silently omit fields that Blockscout otherwise receives from JSON-RPC.

Missing mapping to cover

• Block header: withdrawalsRoot, blobGasUsed, excessBlobGas, parentBeaconBlockRoot, and requestsHash.
• Blob transactions/receipts: maxFeePerBlobGas, blobVersionedHashes, blobGasUsed, and blobGasPrice.
• EIP-7702: map TRX_TYPE_SET_CODE to type 0x4 and emit authorizationList.
• Chain-specific system/deposit transaction fields and system-call placement outside the verified Arbitrum Orbit convention.

Acceptance criteria

• Field-by-field fixtures for Cancun and Prague blocks pass through Blockscout's existing JSON-RPC parsers without defaults replacing real values.
• Frame-level trace parity includes output, value, gas, error, and trace address, not only (depth, type, from, to) counts.
• End-to-end database parity is demonstrated on each newly supported chain family.
• Documentation names the supported chain families explicitly and keeps unverified families opt-in/unsupported.

[DenisCarriere]

Implemented the schema-backed portion in PR #1, commit bb926b50e.

Completed:

• Cancun/Prague block headers: withdrawalsRoot, blobGasUsed, excessBlobGas, parentBeaconBlockRoot, and requestsHash.
• Blob transaction and receipt fields: maxFeePerBlobGas, blobVersionedHashes, blobGasUsed, and blobGasPrice.
• EIP-7702 transaction type 0x4 and authorizationList.
• Access lists and uncle hashes.
• Strict rejection of missing typed fields, unknown transaction types, and mismatched chain-family data.
• Arbitrum system calls are now attached by explicit ArbOS transaction type rather than assumed index; Ethereum protocol system calls remain outside transaction traces, matching debug_traceBlockByNumber.
• Added a strict trace-parity tool comparing transaction, derived trace address, type, addresses, value, gas, input/output, and error.
• Extended database fingerprints for internal transactions, blob transactions, and signed authorizations.

Local verification:

• 16 focused Elixir tests pass in both standalone and CHAIN_TYPE=ethereum builds.
• 11 sidecar tests pass.
• Full umbrella compilation, strict Credo, formatting, syntax, dependency and diff checks pass.

Remaining before this issue can close:

• Run and record strict full-field trace parity against a live Ethereum Cancun/Prague Firehose and archive RPC.
• Run and record RPC-vs-Firehose end-to-end database parity for the Ethereum family.
• Add complete Optimism deposit-specific payload support when the Firehose schema exposes the required fields, then certify Optimism.
• Certify Polygon state-sync/system-call placement and database parity.

Until those live gates pass, FIREHOSE_CHAIN_FAMILY=ethereum is documented as experimental, while Optimism and Polygon fail closed.

[DenisCarriere]

Configuration follow-up in 70c458c40: the custom FIREHOSE_CHAIN_FAMILY setting was removed. The connector now reuses Blockscout native CHAIN_TYPE (arbitrum for the verified Orbit path; ethereum or the default build for the experimental Cancun/Prague mapping). This does not change the remaining live parity gates described above.