Implement Phase 2 features: roles, assessment groups, budget import, Kanban

- Add hierarchical roles: SuperUser Admin (is_superadmin flag), Tenant Admin,
  Tenant User with separate /admin route and admin panel
- Add Assessment Groups module for property type-based assessment rates
  (SFHs, Condos, Estate Lots with different regular/special rates)
- Enhance Chart of Accounts: initial balance on create (with journal entry),
  archive/restore accounts, edit all fields including account number & fund type
- Add Budget CSV import with downloadable template and account mapping
- Add Capital Projects Kanban board with drag-and-drop between year columns,
  table/kanban view toggle, and PDF export via browser print
- Update seed data with assessment groups, second test user, superadmin flag
- Create repeatable reseed.sh script for clean database population
- Fix AgingReportPage Mantine v7 Table prop compatibility

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

frontend/src/components/layout/Sidebar.tsx

@@ -1,4 +1,4 @@
-import { NavLink, ScrollArea } from '@mantine/core';
+import { NavLink, ScrollArea, Divider, Text } from '@mantine/core';
 import { useNavigate, useLocation } from 'react-router-dom';
 import {
   IconDashboard,
@@ -16,13 +16,17 @@ import {
   IconUsers,
   IconFileText,
   IconSettings,
+  IconCrown,
+  IconCategory,
 } from '@tabler/icons-react';
+import { useAuthStore } from '../../stores/authStore';
 
 const navItems = [
   { label: 'Dashboard', icon: IconDashboard, path: '/dashboard' },
   { label: 'Chart of Accounts', icon: IconListDetails, path: '/accounts' },
   { label: 'Transactions', icon: IconReceipt, path: '/transactions' },
   { label: 'Units / Homeowners', icon: IconHome, path: '/units' },
+  { label: 'Assessment Groups', icon: IconCategory, path: '/assessment-groups' },
   { label: 'Invoices', icon: IconFileInvoice, path: '/invoices' },
   { label: 'Payments', icon: IconCash, path: '/payments' },
   { label: 'Budgets', icon: IconReportAnalytics, path: '/budgets/2026' },
@@ -49,6 +53,7 @@ const navItems = [
 export function Sidebar() {
   const navigate = useNavigate();
   const location = useLocation();
+  const user = useAuthStore((s) => s.user);
 
   return (
     <ScrollArea p="sm">
@@ -81,6 +86,22 @@ export function Sidebar() {
           />
         ),
       )}
+
+      {user?.isSuperadmin && (
+        <>
+          <Divider my="sm" />
+          <Text size="xs" c="dimmed" fw={700} tt="uppercase" px="sm" pb={4}>
+            Platform Admin
+          </Text>
+          <NavLink
+            label="Admin Panel"
+            leftSection={<IconCrown size={18} />}
+            active={location.pathname === '/admin'}
+            onClick={() => navigate('/admin')}
+            color="red"
+          />
+        </>
+      )}
     </ScrollArea>
   );
 }