feat: F001 app shell & global layout system

Add PageHeader, UserMenu, NotificationButton, OrganizationContextBadge,
RightContextPanel, CompareTray, and ActivityTimeline; wire all into AppShell.

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

src/App.tsx

@@ -17,6 +17,7 @@ const Shortlists = lazy(() => import('./pages/demand/Shortlists'))
 const ReviewQueue = lazy(() => import('./pages/ops/ReviewQueue'))
 const AIMonitoring = lazy(() => import('./pages/ops/AIMonitoring'))
 const Governance = lazy(() => import('./pages/ops/Governance'))
+const ActivityTimeline = lazy(() => import('./pages/ops/ActivityTimeline'))
 
 function App() {
   return (
@@ -43,6 +44,7 @@ function App() {
             <Route path="/ops/review-queue" element={<ReviewQueue />} />
             <Route path="/ops/ai-monitoring" element={<AIMonitoring />} />
             <Route path="/ops/governance" element={<Governance />} />
+            <Route path="/ops/activity-timeline" element={<ActivityTimeline />} />
           </Route>
 
           <Route path="*" element={<Navigate to="/" replace />} />