`src/script/screen/selectCategories.jsx`: new screen

`index.html`: minor, meta tags that affect appearance when launched from iOS home screen

`app.jsx`: `handleSelectCategoriesChange`

`userListItem.jsx`: support for new skill categories

`profileEdit.jsx`: support for new skill categories; support for new `SelectCategories` screen

`app.scss`: CSS for new `SelectCategories` screen

`src/script/data/categories.js`: temporary sample category data