feat: add CSV import, activity timeline, and AI insights widget

- CSV Import: modal with file picker, auto column mapping, preview table, import progress
- Activity Timeline: new tab on client detail showing all communications, events, status changes
- AI Insights Widget: dashboard card showing stale clients, upcoming birthdays, suggested follow-ups
- Import button on Clients page header

src/lib/api.ts

@@ -1,4 +1,4 @@
-import type { Profile, Client, ClientCreate, Event, EventCreate, Email, EmailGenerate, User, Invite } from '@/types';
+import type { Profile, Client, ClientCreate, Event, EventCreate, Email, EmailGenerate, User, Invite, ActivityItem, InsightsData, ImportPreview, ImportResult, NetworkMatch, NetworkStats } from '@/types';
 
 const API_BASE = import.meta.env.PROD
   ? 'https://api.thenetwork.donovankelly.xyz/api'
@@ -157,6 +157,54 @@ class ApiClient {
     return this.fetch(`/clients/${id}/contacted`, { method: 'POST' });
   }
 
+  // CSV Import
+  async importPreview(file: File): Promise<ImportPreview> {
+    const formData = new FormData();
+    formData.append('file', file);
+    const token = this.getToken();
+    const headers: HeadersInit = token ? { Authorization: `Bearer ${token}` } : {};
+    const response = await fetch(`${API_BASE}/clients/import/preview`, {
+      method: 'POST',
+      headers,
+      body: formData,
+      credentials: 'include',
+    });
+    if (!response.ok) {
+      const error = await response.json().catch(() => ({ error: 'Preview failed' }));
+      throw new Error(error.error || 'Preview failed');
+    }
+    return response.json();
+  }
+
+  async importClients(file: File, mapping: Record<number, string>): Promise<ImportResult> {
+    const formData = new FormData();
+    formData.append('file', file);
+    formData.append('mapping', JSON.stringify(mapping));
+    const token = this.getToken();
+    const headers: HeadersInit = token ? { Authorization: `Bearer ${token}` } : {};
+    const response = await fetch(`${API_BASE}/clients/import`, {
+      method: 'POST',
+      headers,
+      body: formData,
+      credentials: 'include',
+    });
+    if (!response.ok) {
+      const error = await response.json().catch(() => ({ error: 'Import failed' }));
+      throw new Error(error.error || 'Import failed');
+    }
+    return response.json();
+  }
+
+  // Activity Timeline
+  async getClientActivity(clientId: string): Promise<ActivityItem[]> {
+    return this.fetch(`/clients/${clientId}/activity`);
+  }
+
+  // Insights
+  async getInsights(): Promise<InsightsData> {
+    return this.fetch('/insights');
+  }
+
   // Events
   async getEvents(params?: { clientId?: string; type?: string; upcoming?: number }): Promise<Event[]> {
     const searchParams = new URLSearchParams();