iPhone / iPad
Safari does the honors.
Open Steward in Safari.
Safari is the surest path. Recent versions of Chrome and other iOS browsers can also do it from their own Share menu.
Open the menu, then tap Share.
With the compact toolbar, Share lives in the menu beside the address bar. Other toolbar layouts show the square with an arrow directly.
Choose Add to Home Screen.
Tap View More, or scroll the share sheet, if it is not in the first rows.
Keep Open as Web App on, then tap Add.
Steward now lives on your Home Screen with its own icon.
Worth doing on iPhone.In a Safari tab, iOS deletes a site's saved data after seven days of use without a visit, so a character kept there can vanish between sessions. On your Home Screen, Steward is safe from that. The Home Screen app keeps its own save, so copy your character from Data first and paste it there.
Simplified drawing. Menus move between iOS versions, so look for the words in the steps.