feat(shared-types): implement shared API response envelopes

[TheBigWealth89]

Closes #107

---

feat(shared-types): Implement shared API response envelopes

Description

This PR standardizes the API response structure across the BettaPay monorepo by introducing strongly-typed response envelopes. This ensures that all services provide a consistent contract to frontends and API consumers, cleanly delineating successful data payloads from standardized error formats.

Changes Made

• Shared Types Definitions (shared/types/index.ts):
  • Added ApiResponse<T> to wrap single resource payloads and handle errors using the standard ErrorResponse schema.
  • Added PaginatedResponse<T> to standardize list queries, encapsulating the list within data and appending strict pagination metadata (total, limit, offset, hasMore).
• Service Type Safety Refactoring:
  • api-gateway: Updated GET /api/merchants/:id to explicitly return Promise<ApiResponse<Merchant>>. Used the existing createErrorResponse() logic to map NOT_FOUND events directly into the { error: ErrorResponse } envelope without changing core business logic. Added missing @bettapay/shared-types dependency.
  • settlement-engine: Updated GET /api/settlements to explicitly return Promise<PaginatedResponse<SettlementRecord>> and structured the list logic to populate the pagination metadata appropriately.
• Repository Maintenance:
  • Resolved lingering merge conflict markers inside indexer/src/index.ts and addressed a latestLedgerCursor undefined calculation that was disrupting workspace builds.

Type-Safety & Tests

• All 8 workspace packages successfully compile with pnpm -r type-check
• Full build script pnpm -r build passes locally
• All local tests across services continue to pass with zero regressions

[drips-wave]

@TheBigWealth89 Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits

[therealjhay]

Kindly resolve conflict

[TheBigWealth89]

Kindly resolve conflict

I have resolved all conflict