Default title is Roblox, details "Playing {place_name}", and state
"by {creator_name}". The creator comes from the games API response
already fetched for the place name. A text field that expands an
empty placeholder is left out, so the state never shows a bare "by".
text.title sets the activity name, images.* set the large and small icons and hover text, and text.state may be empty to hide it. Text and image fields expand {place_name} and {place_icon}; fields that render empty are omitted. show_place_name: false now also hides the place thumbnail.
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