refactor(archiver): extract l1 synchronizer and factory

[spalladino]

Extracts L1 synchronization logic out of the archiver and into a separate class. Also extracts the createAndSync method into the archiver factory, and lifts some more methods to the ArchiveSourceBase.

Created Files

• archiver/src/archiver/archiver_l1_synchronizer.ts (~800 lines): New class that extracts all L1 synchronization logic from the Archiver, including:
  • syncFromL1() - Main sync orchestration
  • handleCheckpoints() - Checkpoint retrieval and validation
  • handleL1ToL2Messages() - L1→L2 message fetching
  • handleEpochPrune() - Epoch pruning detection
  • Implements Traceable interface for distributed tracing

Modified Files

• archiver/src/archiver/archiver.ts: Removed ~630 lines of L1 sync code; constructor now accepts synchronizer and events as injected dependencies
• archiver/src/factory.ts: Consolidated Archiver.createAndSync() logic into createArchiver(); creates synchronizer/events and injects them
• archiver/src/archiver/index.ts: Added export for ArchiverL1Synchronizer
• aztec/src/cli/cmds/start_archiver.ts: Changed from Archiver.createAndSync() to createArchiver()
• archiver/src/archiver/archiver.sync.test.ts and archiver.test.ts: Updated to create synchronizer and events before creating Archiver

Architectural Change

• L1 sync logic is now separated from the Archiver into ArchiverL1Synchronizer
• Factory is the single entry point for creating an archiver with all its dependencies
• Dependency injection pattern for synchronizer and event emitter

This aligns with the plan goal of "clean separation of the archiver into syncing (L1 sync) vs datastore (storage + reads)".

[AztecBot]

Flakey Tests

🤖 says: This CI run detected 2 tests that failed, but were tolerated due to a .test_patterns.yml entry.

\033FLAKED\033 (8;;http://ci.aztec-labs.com/bcc703c003416985�bcc703c0034169858;;�): yarn-project/end-to-end/scripts/run_test.sh web3signer src/composed/web3signer/e2e_multi_validator_node_key_store.test.ts (36s) (code: 1) (\033Santiago Palladino\033: refactor(archiver): extract l1 synchronizer)
\033FLAKED\033 (8;;http://ci.aztec-labs.com/b602a8d65286783b�b602a8d65286783b8;;�):  yarn-project/end-to-end/scripts/run_test.sh simple src/e2e_epochs/epochs_invalidate_block.parallel.test.ts "proposer invalidates multiple blocks" (604s) (code: 124) group:e2e-p2p-epoch-flakes (\033Santiago Palladino\033: refactor(archiver): extract l1 synchronizer)

[spalladino]

Closing in favor of #19564