update monthly aggregation and docs

README.md

@@ -7,6 +7,7 @@ vCTP is a vSphere Chargeback Tracking Platform, designed for a specific customer
 - Snapshots are registered in `snapshot_registry` so regeneration via `/api/snapshots/aggregate` can locate the correct tables (fallback scanning is also supported).
 - Reports (XLSX with totals/charts) are generated automatically after hourly, daily, and monthly jobs and written to a reports directory.
 - Hourly totals in reports are interval-based: each row represents `[HH:00, HH+1:00)` and uses the first snapshot at or after the hour end (including cross-day snapshots) to prorate VM presence by creation/deletion overlap.
+- Monthly aggregation reports include a Daily Totals sheet with full-day interval labels (`YYYY-MM-DD to YYYY-MM-DD`) and prorated totals derived from daily summaries.
 - Prometheus metrics are exposed at `/metrics`:
   - Snapshots/aggregations: `vctp_hourly_snapshots_total`, `vctp_hourly_snapshots_failed_total`, `vctp_hourly_snapshot_last_unix`, `vctp_hourly_snapshot_last_rows`, `vctp_daily_aggregations_total`, `vctp_daily_aggregations_failed_total`, `vctp_daily_aggregation_duration_seconds`, `vctp_monthly_aggregations_total`, `vctp_monthly_aggregations_failed_total`, `vctp_monthly_aggregation_duration_seconds`, `vctp_reports_available`
   - vCenter health/perf: `vctp_vcenter_connect_failures_total{vcenter}`, `vctp_vcenter_snapshot_duration_seconds{vcenter}`, `vctp_vcenter_inventory_size{vcenter}`