Show properties that aren't in any property group

Problem / context

Operators who add properties regularly have no way to see which ones haven't been added to a property group. Anything left out silently misses group-scoped rules, reports, knowledge snippets and alerts. Today the only way to find them is to compare the property list against every group by hand, or to use the API.

Requested capability

A filter or view that lists active properties not assigned to any property group.

Detail / spec

• "Not in any group" filter on the Properties page (and/or a count on the Property Groups page).
• Highlight newly activated properties that haven't been grouped yet.
• Exportable, so the list can be worked through in bulk.
• Respects Auto Groups: properties covered by an auto group count as grouped.

Acceptance criteria

• A user can see every active property that isn't in any group, without the API.
• Newly added properties appear in the list until they're assigned to a group.
• The list can be exported.