- Updated session variables to use 'authorization' array instead of 'username' for user identification across multiple files.
- Introduced a new function `getUserPermissions` to consolidate user permissions retrieval based on assigned roles.
- Modified API calls to use the new authorization structure and updated endpoints to v2.
- Enhanced language support by adding 'PL' to the list of supported languages.
- Cleaned up redundant code and improved session management during user login and registration processes.
- Added a new API endpoint for fetching user permissions based on user ID.
- Added invoice generation logic using DomPDF.
- Integrated invoice data retrieval from the API.
- Implemented language determination for invoices based on customer data.
- Added options to email invoices to customers and admin.
- Included HTML output option for direct viewing in the browser.
- Ensured proper redirection and error handling throughout the process.
- Updated action buttons across multiple files to use icons (e.g., "Save" to "💾+", "Delete" to "X").
- Replaced "Cancel" button text with a left arrow (←) for a more intuitive navigation experience.
- Removed unnecessary action columns from tables to streamline the interface.
- Enhanced table rows to be clickable for better user interaction, redirecting to relevant management pages.
- Adjusted font sizes and styles in CSS for improved readability and aesthetics.
- Standardized back button functionality to use a left arrow across various pages.
