perf(contract): make transfer pagination bounded and counter-overflow safe

[arisu6804]

Problem

Growing transfer counters and unbounded page requests can overflow or exceed transaction limits.

Objective

Deliver a production-quality improvement to transfer index and pagination state that creates measurable value for correctness, security, reliability, performance, or maintainability.

Implementation scope

• Use checked counters, bounded page size, deterministic cursors, and safe behavior at maximum values.

Acceptance criteria

• Pagination remains valid at counter boundaries; oversized pages fail or cap; no transfer is skipped or repeated.

Required validation

• Boundary counter, pagination, concurrent-write, and limit tests.
• Existing tests and CI remain passing.
• Add regression coverage for the original failure mode.
• Do not weaken, delete, or skip unrelated tests to obtain a green build.

PR quality bar

• Keep the PR focused and explain design tradeoffs, compatibility impact, and test evidence.
• Avoid typo-only, documentation-only, cosmetic-only, or unrelated refactor submissions.

Out of scope

• Broad rewrites not required by the acceptance criteria.
• Changes to unrelated services, contracts, or user flows.

[AbayomiCoded]

Hi @arisu6804 I can implement robust checked counters, bounded pagination with deterministic cursors, and comprehensive boundary/concurrency tests to prevent overflow and ensure no transfers are skipped or repeated.

[grantfox-oss]

🦊 GrantFox — @AbayomiCoded has been assigned to this issue as part of the Third Campaign campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #188)
2. Your PR will be reviewed by the RemitFlow maintainers

Good luck! Track your progress on GrantFox.