rounded category boxes, redesigned add recipe buttons in mealplan, display categories in recipeview, improved GUI

added header to ingredient-creator; in the shopping list flipStatus works and checkboxes are still checked after switching pages

added app icon, added "back" button to recipe creator. now creating recipes and adding them to the recipe manager

refactoring RecipeSearch, slight visual changes, now selecting ingredients in recipe creator and validating number inputs

Split GUI and the model into two classes. File manager is now fully implemented. the branch will be merged with main