Fix user deletion to preserve data integrity

Updates the `deleteUser` method to handle foreign key constraints by transferring user-created records to an admin user before deletion, ensuring data integrity and preventing errors.

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Replit-Commit-Session-Id: a8a78c07-e900-425c-a577-5b4c5894379d
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replit.md

@@ -75,4 +75,18 @@ Preferred communication style: Simple, everyday language.
 - **Development Server**: Vite dev server
 
 ### Other Integrations
-- **NocoDB Integration**: Configurable for invoice verification and data synchronization.
+- **NocoDB Integration**: Configurable for invoice verification and data synchronization.
+
+## Recent Changes
+
+### August 11, 2025 - User Deletion Fix
+- **Issue**: Foreign key constraint errors when deleting users who created customer orders or other records
+- **Root Cause**: User records were referenced by multiple tables (customer_orders, deliveries, DLC products, etc.)
+- **Solution Implemented**:
+  - Enhanced deleteUser method with database transaction for atomicity
+  - Dynamic admin user lookup instead of hardcoded fallback user
+  - Ownership transfer of all user-created records to existing admin before deletion
+  - Comprehensive handling of all foreign key relationships
+  - Graceful error handling when no admin user exists
+- **Tables Handled**: customer_orders, orders, deliveries, publicities, dlcProducts, tasks, nocodbConfig, userGroups, userRoles
+- **Result**: Safe user deletion while preserving business data integrity