Add sync anomaly detection, BU drift monitoring, and findings count investigation

- Add BU drift checker that classifies archived findings as BU reassignment,
  severity drift, closure, or decommission via unfiltered Ivanti API queries
- Add post-sync anomaly summary with significance threshold and classification
  breakdown stored in ivanti_sync_anomaly_log table
- Add per-finding BU tracking that detects BU changes across syncs and records
  them in ivanti_finding_bu_history table
- Add drift guard that skips trend history writes when total drops more than 50%
- Add CLOSED_GONE archive state for findings that vanish from the closed set
- Add anomaly banner UI on Vulnerability Triage page for significant sync changes
- Add API endpoints for anomaly latest/history and BU change tracking
- Add diagnostic scripts for drift checking and BU reassignment verification
- Add investigation document and xlsx export for the April 2026 BU reassignment
  incident where 109 findings were moved to SDIT-CSD-ITLS-PIES
- Migrations required: add_closed_gone_state.js, add_sync_anomaly_tables.js

frontend/src/components/pages/ReportingPage.js

@@ -4,6 +4,7 @@ import { RefreshCw, Loader, AlertCircle, PieChart, ChevronUp, ChevronDown, Chevr
 import * as XLSX from 'xlsx';
 import { useAuth } from '../../contexts/AuthContext';
 import IvantiCountsChart from './IvantiCountsChart';
+import AnomalyBanner from './AnomalyBanner';
 import CveTooltip from '../CveTooltip';
 import RedirectModal from '../RedirectModal';
 import AtlasBadge from '../AtlasBadge';
@@ -4633,6 +4634,7 @@ export default function VulnerabilityTriagePage({ filterDate, filterEXC }) {
             {/* ----------------------------------------------------------------
                 Panel 1.5 — Open vs Closed trend over time
             ---------------------------------------------------------------- */}
+            {metricsTab === 'ivanti' && <AnomalyBanner />}
             {metricsTab === 'ivanti' && <IvantiCountsChart />}
 
             {/* ----------------------------------------------------------------