[HARD][STELLAR INDEXER] Add contiguous checkpoints, dead-letter replay, and gap detection

[Obiajulu-gif]

Problem

lib/stellar/indexer.ts can advance to a later cursor after an earlier event in the page fails, permanently skipping financial data.

Scope

• Persist raw envelopes first, keyed by network, stream, ledger, transaction, and event index.
• Advance only through the highest contiguous successful sequence.
• Add per-stream leases with fencing for multiple replicas.
• Quarantine poison events with original payload and replay metadata.
• Add bounded replay, backfill, and rebuild commands.
• Detect missing ranges, wrong network/contract, stalls, and projection lag.
• Use a transaction or recoverable inbox for event/checkpoint writes.

Acceptance criteria

• Failure at N prevents checkpoint movement past N.
• Restart at any boundary produces the same result.
• Concurrent workers have single-writer semantics.
• Replay never duplicates financial effects.
• Health reports source, raw and projection checkpoints, lag, and oldest failure.

Required tests

Middle-page poison event, crash around every persistence step, lease race, full pagination, provider retry, and clean-rebuild equivalence.

Non-goals

Guarantee lossless ingestion; do not classify every Stellar operation.

[muokwejosh-cloud]

Hi maintainer, pls assign me to work on this issue

[grantfox-oss]

🦊 GrantFox — @muokwejosh-cloud has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #129)
2. Your PR will be reviewed by the Chainmove maintainers

Good luck! Track your progress on GrantFox.