closes #392

Features

• Stats Cards: Total Assets, Assets by Status, Total Value, Attention Needed with trend indicators
• Charts: Pie chart (Assets by Category), Bar chart (Assets by Department), Line chart (Asset Registrations Over Time)
• Activity Feed: Last 10 activities (created, assigned, transferred, retired) with timestamps and asset links
• Quick Actions: Register Asset, Generate Report, Bulk Import, Request Asset with navigation

Technical Implementation

• API Endpoints: /api/dashboard/stats, /api/dashboard/activities, /api/dashboard/charts with date range support
• Real-time Updates: Configurable polling (10s/30s/60s) with Live/Paused toggle
• Date Range Filter: 7d/30d/90d/6m/12m selector that filters all widgets
• Customizable Layout: Drag-and-drop widget rearranging with persisted order
• React Query: Data fetching with caching and loading states
• Responsive Design: Works on all screen sizes with equal-height cards

Components

• StatsSection, StatusBreakdown, DepartmentBreakdown, RegistrationChart, CategoryChart, ActivityFeed, QuickActions

Acceptance Criteria

✅ Dashboard loads within 2 seconds
✅ All stats display accurate data from API
✅ Charts are responsive and interactive
✅ Activity feed updates automatically
✅ Quick actions navigate to correct pages
✅ Dashboard works on all screen sizes
✅ Loading states are smooth and informative