feat(triage): Ivanti findings trend chart + rename Reporting to Vulnerability Triage

Add time-based open/closed tracking for Ivanti findings (Tier 2 from
the reporting recommendations doc) and rename the Reporting page to
Vulnerability Triage to better reflect its purpose.

Backend — ivantiFindings.js:
  - Create ivanti_counts_history table (appended on every sync, never
    overwritten — Option B from design discussion)
  - INSERT snapshot after each successful syncClosedCount() call
  - GET /api/ivanti/findings/counts/history endpoint — returns last
    snapshot per calendar day using ROW_NUMBER window function, so
    multiple daily syncs collapse to the end-of-day value

Frontend:
  - New IvantiCountsChart component: collapsible dual-line chart
    (open vs closed) with dark tooltip, delta label showing change
    since previous day, and graceful no-data states
  - Chart placed between the donut metrics panel and the findings table
    on the Vulnerability Triage page
  - Renamed page: 'reporting' → 'triage' (page ID, nav label, component
    export, all cross-file references)
  - ComplianceDetailPanel "View in Reporting" link updated to "View in
    Triage" and navigates to the correct page ID

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/components/NavDrawer.js

@@ -3,7 +3,7 @@ import { X, Home, BarChart2, BookOpen, Download, ShieldCheck } from 'lucide-reac
 
 const NAV_ITEMS = [
   { id: 'home',           label: 'Home',           icon: Home,        color: '#0EA5E9', description: 'Main dashboard'            },
-  { id: 'reporting',      label: 'Reporting',      icon: BarChart2,   color: '#F59E0B', description: 'Reports & analytics'       },
+  { id: 'triage',         label: 'Vuln Triage',    icon: BarChart2,   color: '#F59E0B', description: 'Active findings & CVE triage' },
   { id: 'compliance',     label: 'Compliance',     icon: ShieldCheck, color: '#14B8A6', description: 'AEO posture & metrics'     },
   { id: 'knowledge-base', label: 'Knowledge Base', icon: BookOpen,    color: '#10B981', description: 'Articles & documentation'   },
   { id: 'exports',        label: 'Exports',        icon: Download,    color: '#8B5CF6', description: 'Export data & reports'      },