Save new user labels so their assigned IDs exist in storage.

source/options/user-label-editor.tsx

@@ -58,15 +58,15 @@ class App extends Component<Props, State> {
     );
 
     const id = await newUserLabelId();
-    userLabels.push(
-      await createValueUserLabel({
+    const userLabel = await createValueUserLabel({
       color: "#ff00ff",
       id,
       priority: 0,
       text: "New Label",
       username: existingUserLabel?.value.username ?? newLabelUsername,
-      }),
-    );
+    });
+    await userLabel.save();
+    userLabels.push(userLabel);
     unsavedUserLabelIds.add(id);
     this.setState({unsavedUserLabelIds, userLabels});
   };