feat(chain-watcher): Publish chain transactions to Redis Streams

[geminimir]

Summary

After detecting a chain transaction, publish it to a Redis Stream so the Correlator and Finality Tracker can consume it. Implements idempotent publishing using chain+tx_hash deduplication.

Changes

• Add RedisTransactionPublisher class for publishing to chain-transactions stream
• Implement idempotent publish using chain:tx_hash as dedup key with 7-day TTL
• Add ChainTransactionMessage type to shared package with required fields:
  • chain, tx_hash, block_number, block_hash, amount, sender, receiver, token_contract, detected_at
• Add fromTransferLog static helper for converting TransferLog to ChainTransactionMessage
• Add ioredis dependency for Redis connectivity

How to Test

1. npm ci
2. npm run typecheck
3. npm test --workspace=@stripeonchain/chain-watcher

Tests

• Tests added/updated (12 new tests for TransactionPublisher)
• All tests pass (npm test - 51 total)
• Lint passes (npm run lint)
• Type-check passes (npm run typecheck for chain-watcher)
• Formatting passes (npm run format:check)

Test Coverage

• New tx appears in stream after detection
• Duplicate tx is not re-published (idempotency)
• Same tx_hash on different chains treated as separate
• Custom stream key support
• TransferLog to message conversion

Checklist

• No secrets or credentials committed
• Migrations run cleanly up and down (npm run migrate:up / npm run migrate:down)
• Docker Compose starts without errors (docker compose up)

Related Issues

Closes #15

Made with Cursor