Updates the StoreItemSchema to handle various input formats for the 'purchased' field, including strings and numbers.
This ensures that the application can correctly interpret boolean values from different sources, preventing data validation errors and improving the user experience.
Adds a preprocess function to the schema to convert string values like "on", "true", "1", "off", "false", and "0", and number values of 1 and 0 to their respective boolean equivalents before validation.