cleanup: defaultProps -> JS default params on our function components

React 19 drops defaultProps on function components. Converted the 9 of
ours that used it (App, Navigation, ReSendEmail, Reconnect, OAuthLoginButton,
PageHeader, Page, EditDocument, EditSubscription) to destructured default
params; App defaults userId/emailAddress in its withTracker instead (it
spreads {...props} widely). Class components keep defaultProps (still
supported). The only defaultProps warnings left are from the react-share
npm package (CreatedButton/Icon), not our code. REST smoke byte-identical.

imports/ui/layouts/App/App.js

@@ -165,11 +165,6 @@ const App = props => (
   </div>
 );
 
-App.defaultProps = {
-  userId: '',
-  emailAddress: ''
-};
-
 App.propTypes = {
   loading: PropTypes.bool.isRequired,
   i18nReady: PropTypes.object.isRequired,
@@ -197,8 +192,9 @@ export default withTracker(() => {
     authenticated: !loggingIn && !!userId,
     name: name || emailAddress,
     roles: (user && user.roles) || [],
-    userId,
-    emailAddress,
+    // default to '' here (was App.defaultProps, unsupported on fn components in React 19)
+    userId: userId || '',
+    emailAddress: emailAddress || '',
     emailVerified: user && user.emails ? user && user.emails && user.emails[0].verified : true
   };
 })(App);