API-6 Document batch/close and batch/summary endpoints in Cloud API REST docs

[ecunado]

This PR updates the Cloud API documentation to cover the new batch endpoints:

• POST /batch/close
• POST /batch/summary

Changes

• REST endpoints (restendpoints.md)

  • Extended the Batch Operations section to include:
    • POST /batch/close
    • POST /batch/summary:
      • Describes purpose (retrieve batch totals and status for a given terminal + batchNumber)
      • Documents required fields: deviceType, serialNumber, batchNumber
      • Adds example requests and responses
      • Documents validation error behaviour (422 VALIDATION_FAILED when batchNumber is missing)

• Objects (restobjects.md)

  • Added BatchSummaryRequest:
    • References POST /batch/summary
    • Includes deviceType, serialNumber, batchNumber and optional customerReference
  • Added BatchSummaryResponse:
    • Documents batchNumber, batchStatus, netAmount, transactionCount,
      issuerResponseCode, issuerResponseText, customFields.entry[], and httpStatus
    • Includes example JSON payload