Add complete customer management system to CRM

[steve8708]

Implements a comprehensive customer management system for the CRM module with the following components:

New Components:

• CustomerDetailsCard: Dialog component for viewing detailed customer information with avatar, contact details, and formatted data display
• CustomerDialog: Form dialog for creating new customers and editing existing ones with validation and loading states
• CustomersDataGrid: DataGrid Pro component with pagination, search, and action buttons for customer operations

New Utilities:

• customer.ts: TypeScript type definitions for Customer, API requests/responses, and related interfaces
• customersApi.ts: API integration layer with methods for fetching, creating, updating, and deleting customers

Enhanced Pages:

• Customers.tsx: Transformed from placeholder to full-featured customer management interface with search, pagination, CRUD operations, and snackbar notifications

Features Added:

• Server-side pagination and search functionality
• Customer avatar display and formatted data presentation
• Create, Read, Update, Delete operations for customers
• Confirmation dialogs for destructive actions
• Loading states and error handling
• Responsive design with Material-UI components
• Integration with Builder.io users API

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To clone this PR locally use the Github CLI with command gh pr checkout 12

🔗 Edit in Builder.io

[steve8708]

@builderio-bot move this to be its own component in a new file and use it here

[builder-io-integration]

I will get right to work!