Implement boxes management module with auto-numbered box creation

- Add boxes_crates database table with BIGINT IDs and 8-digit auto-numbered box_numbers
- Implement boxes CRUD operations (add, edit, update, delete, delete_multiple)
- Create boxes route handlers with POST actions for all operations
- Add boxes.html template with 3-panel layout matching warehouse locations module
- Implement barcode generation and printing with JsBarcode and QZ Tray integration
- Add browser print fallback for when QZ Tray is not available
- Simplify create box form to single button with auto-generation
- Fix JavaScript null reference errors with proper element validation
- Convert tuple data to dictionaries for Jinja2 template compatibility
- Register boxes blueprint in Flask app initialization

scriptqz .txt

@@ -0,0 +1,2 @@
+<script src="{{ url_for('static', filename='js/qz-tray.js') }}"></script>
+<script src="{{ url_for('static', filename='js/qz-printer.js') }}"></script>