4.8.38 dev v1 - #658

…ts (KB-iGOT#655)

* KB-14010 | Q12 | BE | Blended Program Enhancements | Batch-wise reports

- Fixed Cassandra column mappings for batch detail fields (name, start_date,
  end_date, enrollment_enddate)
- Added contextType = 'Blended Program Consumption Report' as composite key
  for all V2 Cassandra operations
- Introduced BP_ENROLMENT_REPORT_TABLE_V2 (bp_enrolment_report_v2) for V2
- Made report file name prefix configurable via bp.report.v2.file.name.prefix
- Added POST /bp/v2/bpreport/status API to fetch V2 report status
- Fixed updateReportStatus() call sites: status param always before contextType

* KB-14010 | Q12 | BE | Blended Program Enhancements | BP Report V2 status API - NPE fix and null check

- Added null/empty check on request body in getBPReportStatusV2 to prevent
  NPE when requestBody does not contain the nested request map
- Uses MapUtils.isEmpty for consistency with the rest of the codebase

…ts (KB-iGOT#660)

- Added POST /bp/v2/bpreport/list API to fetch BP reports from both V1
  (bp_enrolment_report) and V2 (bp_enrolment_report_v2) tables in a single
  unified response
- Added API constant API_BP_REPORT_LIST = "api.bp.report.list"
- Response structure identical to individual status APIs (content + count)
- V2 records filtered by contextType = 'Blended Program Consumption Report'
- Extracted Cassandra fetch logic into private fetchCombinedReports() to keep
  the public method focused on validation and response building
- Added interface Javadoc for getBPReportList in BPReportsServiceV2