* feat: add language preference for customers to support invoice localization
- Introduced language support for invoices, allowing customers to choose between Swedish and English.
- Updated invoice PDF generation to reflect the selected language for titles, labels, and messages.
- Enhanced email templates to generate content in the customer's preferred language.
- Added migration to include a language column in the customers table with a default value of Swedish.
- Updated tests to verify correct language usage in invoice emails and PDFs.
* fix: debounce API requests in InvoicePreviewCard and update F-skatt terminology in email templates
* Fixed user issues
* feat: add personal_number column to customers for individual identification
* feat: add personal_number field to makeCustomer function for enhanced customer identification
* feat: add personal_number column with constraint check for customer identification
Mattsson