feat(compliance): add AEO compliance frontend

- CompliancePage: team tabs (STEAM/ACCESS-ENG), metric health cards with
  click-to-filter, device table with Active/Resolved tabs, hostname search,
  seen-count badges, notes indicator, empty/loading/error states
- ComplianceUploadModal: phased flow (idle→upload→preview→commit→done),
  drag-and-drop xlsx drop zone, diff summary before commit
- ComplianceDetailPanel: slide-out panel with failing metrics, surfaced
  extra fields (CVEs, SLA, OS, Splunk), upload history, notes timeline,
  per-metric note add with Ctrl+Enter submit
- NavDrawer: add Compliance nav item (teal, ShieldCheck icon)
- App.js: import and render CompliancePage on compliance route
- Fix SQL join bug in compliance route (lu ON upload_id = lu.id)
- Fix groupByHostname to use max last_seen across all metric rows

frontend/src/App.js

@@ -13,6 +13,7 @@ import CalendarWidget from './components/CalendarWidget';
 import ReportingPage from './components/pages/ReportingPage';
 import KnowledgeBasePage from './components/pages/KnowledgeBasePage';
 import ExportsPage from './components/pages/ExportsPage';
+import CompliancePage from './components/pages/CompliancePage';
 import './App.css';
 
 const API_BASE = process.env.REACT_APP_API_BASE || 'http://localhost:3001/api';
@@ -1043,6 +1044,7 @@ export default function App() {
 
         {/* Page content */}
         {currentPage === 'reporting'      && <ReportingPage filterDate={calendarFilter} filterEXC={reportingExcFilter} />}
+        {currentPage === 'compliance'     && <CompliancePage />}
         {currentPage === 'knowledge-base' && <KnowledgeBasePage />}
         {currentPage === 'exports'        && <ExportsPage />}