feat: audit log page, meeting prep modal, communication style, error boundaries + toast

- AuditLogPage: filterable table with expandable details (admin only)
- MeetingPrepModal: AI-generated meeting briefs with health score, talking points, conversation starters
- Communication Style section in Settings: tone, greeting, signoff, writing samples, avoid words
- ErrorBoundary wrapping all page routes with Try Again button
- Global toast system with API error interceptor (401/403/500)
- ToastContainer with success/error/warning/info variants
- Print CSS for meeting prep
- Audit Log added to sidebar nav for admins
- All 80 frontend tests pass, clean build

src/pages/ClientDetailPage.tsx

@@ -17,6 +17,7 @@ import ClientForm from '@/components/ClientForm';
 import EmailComposeModal from '@/components/EmailComposeModal';
 import ClientNotes from '@/components/ClientNotes';
 import LogInteractionModal from '@/components/LogInteractionModal';
+import MeetingPrepModal from '@/components/MeetingPrepModal';
 import type { Interaction } from '@/types';
 
 export default function ClientDetailPage() {
@@ -31,6 +32,7 @@ export default function ClientDetailPage() {
   const [showEdit, setShowEdit] = useState(false);
   const [showCompose, setShowCompose] = useState(false);
   const [showLogInteraction, setShowLogInteraction] = useState(false);
+  const [showMeetingPrep, setShowMeetingPrep] = useState(false);
   const [deleting, setDeleting] = useState(false);
   const { togglePin, isPinned } = usePinnedClients();
 
@@ -120,6 +122,10 @@ export default function ClientDetailPage() {
             <Phone className="w-4 h-4" />
             <span className="hidden sm:inline">Log Interaction</span>
           </button>
+          <button onClick={() => setShowMeetingPrep(true)} className="flex items-center gap-2 px-3 py-2 bg-purple-50 text-purple-700 dark:bg-purple-900/30 dark:text-purple-300 rounded-lg text-sm font-medium hover:bg-purple-100 dark:hover:bg-purple-900/50 transition-colors">
+            <Briefcase className="w-4 h-4" />
+            <span className="hidden sm:inline">Meeting Prep</span>
+          </button>
           <button onClick={() => setShowCompose(true)} className="flex items-center gap-2 px-3 py-2 bg-blue-50 text-blue-700 dark:bg-blue-900/30 dark:text-blue-300 rounded-lg text-sm font-medium hover:bg-blue-100 dark:hover:bg-blue-900/50 transition-colors">
             <Sparkles className="w-4 h-4" />
             <span className="hidden sm:inline">Generate Email</span>
@@ -355,6 +361,14 @@ export default function ClientDetailPage() {
         onGenerated={(email) => setEmails((prev) => [email, ...prev])}
       />
 
+      {/* Meeting Prep Modal */}
+      <MeetingPrepModal
+        isOpen={showMeetingPrep}
+        onClose={() => setShowMeetingPrep(false)}
+        clientId={client.id}
+        clientName={`${client.firstName} ${client.lastName}`}
+      />
+
       {/* Log Interaction Modal */}
       <LogInteractionModal
         isOpen={showLogInteraction}