Refactor application to MVC architecture with Flask blueprints

Major architectural refactoring to improve code organization, maintainability, and scalability:

- Implement MVC pattern with clear separation of concerns
- Organize code into blueprints for different functional areas (main, tenant, admin, api)
- Create models layer to encapsulate all database operations
- Create services layer for business logic (auth, product, barcode)
- Implement application factory pattern for better testability
- Add environment-based configuration management
- Remove old monolithic app.py and consolidate routes

New structure:
- app/models/ - Database operations (Tenant, Product, ARField, Settings)
- app/services/ - Business logic (Auth, Product, Barcode services)
- app/blueprints/ - Controllers organized by function
- app/config.py - Environment configurations
- run.py - Application entry point

All routes remain backward compatible. No changes to API or templates functionality.

src/run.py

@@ -0,0 +1,20 @@
+import os
+import shutil
+from app import create_app
+from app.models import TenantModel
+
+# Create application
+app = create_app(os.environ.get('FLASK_ENV', 'development'))
+
+if __name__ == '__main__':
+    with app.app_context():
+        # Migrate existing data from JSON if needed (backward compatibility)
+        # Note: This is for the old database.py migration - keeping for reference
+        # but in the new structure, this would be handled differently
+
+        # Clean up any accidentally created reserved tenants
+        deleted_count = TenantModel.cleanup_reserved()
+        if deleted_count > 0:
+            print(f"Cleaned up {deleted_count} reserved tenant(s)")
+
+    app.run(port=5555, host="0.0.0.0", debug=True)