Flutter CRM App Builder: Generate Complete Cross-Platform Customer Relationship Management Code

## Flutter CRM App Generator Prompt

You are an expert Flutter developer specializing in cross-platform CRM applications. Generate a complete, production-ready Flutter app for Customer Relationship Management (CRM) based on the following specifications. Use the latest Flutter version, Material Design 3 for UI, Firebase for backend (authentication, Firestore database, real-time updates), and ensure full responsiveness for iOS and Android.

### Core Requirements
- **App Name**: FlutterCRM Pro
- **Key Features**:
  - User authentication (email/password, Google sign-in).
  - Dashboard with key metrics (total customers, recent activities, sales pipeline).
  - Contacts management: Add/edit/view/search customers with fields like name, email, phone, company, notes, tags.
  - Leads & Opportunities: Track sales pipeline stages (lead, qualified, proposal, closed).
  - Activities: Tasks, calls, emails, meetings with reminders and calendar integration.
  - Reports & Analytics: Charts for sales trends, customer segmentation using charts_flutter.
  - Customizable modules: Allow users to add custom fields.
  - Real-time collaboration: Sync data across devices, notifications.
- **UI/UX**: Intuitive, modern design with navigation drawer, bottom nav bar, search, filters, dark mode support.

### Project Structure
Provide the full code organized as follows:
1. **pubspec.yaml**: List all dependencies (flutter, firebase_core, cloud_firestore, firebase_auth, google_sign_in, charts_flutter, intl, etc.).
2. **lib/main.dart**: App entry with theme and routing.
3. **lib/models/**: Dart classes for Contact, Lead, Activity, etc.
4. **lib/services/**: Firebase services for auth, database.
5. **lib/screens/**: DashboardScreen, ContactsScreen, LeadsScreen, ReportsScreen, etc.
6. **lib/widgets/**: Reusable components like CustomerCard, ChartWidget.

### Example Screens
- **Dashboard Example**:
  ```dart
  // Pseudo-code snippet
  class DashboardScreen extends StatelessWidget {
    @override
    Widget build(BuildContext context) {
      return Scaffold(
        appBar: AppBar(title: Text('Dashboard')),
        body: Column(
          children: [
            MetricsCards(), // Total customers, revenue, etc.
            RecentActivitiesList(),
          ],
        ),
      );
    }
  }
  ```

### Additional Instructions
- Use Provider or Riverpod for state management.
- Implement offline support with Firestore caching.
- Add pull-to-refresh, infinite scrolling for lists.
- Ensure data privacy with secure storage.
- Generate APK build instructions.
- Output code in a single, copy-paste ready format with comments.
- Test for errors and optimize performance.

Generate the FULL app code now. Start with pubspec.yaml.