feat(22-06): campaigns list page + Phishing nav entry (D-00, D-02)

- app/phishing/page.tsx: minimal DataTable-backed campaigns list, row click
  navigates to /phishing/tickets/{firstReportTicketId}, EmptyState when no
  campaigns exist yet
- components/navigation/app-navigation.tsx: add flat "Phishing" nav item
  (ShieldAlert icon) immediately after PAX8, visible to all roles (every
  role has phishing:read)

components/navigation/app-navigation.tsx

@@ -19,6 +19,7 @@ import {
   AlertTriangle,
   ChevronDown,
   ShoppingCart,
+  ShieldAlert,
 } from 'lucide-react';
 import {
   NavigationMenu,
@@ -67,6 +68,12 @@ const navigationItems: NavItem[] = [
     icon: ShoppingCart,
     description: 'PAX8 companies, subscriptions, and cost breakdown'
   },
+  {
+    title: 'Phishing',
+    href: '/phishing',
+    icon: ShieldAlert,
+    description: 'Phishing/spam campaign triage, evidence, and remediation approval'
+  },
   {
     title: 'Backup Status',
     icon: HardDrive,