Add per-investor exposure cap aggregation across offerings with realtime checks

[thlpkee20-wq]

Description

Investor exposure caps currently apply per-offering. Add cross-offering aggregation that enforces a global cap per investor identity, evaluated at submission time using a serializable read against current commitments.

Requirements and context

• Must be secure, tested, and documented
• Should be efficient and easy to review
• Relevant code: src/services/investmentService.ts, src/db/repositories/investmentRepository.ts
• Aggregate must include pending and confirmed states

Suggested execution

• Fork the repo and create a branch
• git checkout -b feat/global-investor-cap
• Implement changes
  • Add investor_cap_config with effective date
  • Add aggregator query with serializable isolation
  • Reject submission with structured error code
• Validate security and correctness assumptions

Test and commit

• Run tests
  • npm test
• Cover edge cases
  • Concurrent submissions across offerings, cap reduction mid-flight
• Include test output and notes

Example commit message

feat: global per-investor exposure cap enforcement

Guidelines

• Minimum 95 percent test coverage
• Clear documentation
• Timeframe: 96 hours

[Elsa-tech2026]

@Elsa-tech2026 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

I’m a full-stack and smart contract developer eager to learn and add value to this project. Please consider assigning this task to me!

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Elsa-tech2026 to this issue.

[Zainab5970]

@Zainab5970 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

please can i work on the issue

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Zainab5970 to this issue.