feat: add TotalCount field to PageInfo

test: add TotalCount assertions to existing tests

pagination.go

@@ -99,6 +99,7 @@ func GetPage[T any](items []T, first *int, after *string, last *int, before *str
 		HasNextPage:     eIx < len(items),
 		HasPreviousPage: sIx > 0,
 		EndCursor:       ptr(EncodeCursor(fn(page[len(page)-1]))),
+		TotalCount:      len(items),
 	}
 }
 
@@ -111,4 +112,5 @@ type PageInfo struct {
 	HasNextPage     bool
 	HasPreviousPage bool
 	EndCursor       *string
+	TotalCount      int
 }