fix onboarding on web

src/state/models/ui/shell.ts

@@ -140,6 +140,10 @@ export interface PreferencesHomeFeed {
   name: 'preferences-home-feed'
 }
 
+export interface OnboardingModal {
+  name: 'onboarding'
+}
+
 export type Modal =
   // Account
   | AddAppPasswordModal
@@ -175,6 +179,9 @@ export type Modal =
   // Generic
   | ConfirmModal
 
+  // Onboarding (only used on web)
+  | OnboardingModal
+
 interface LightboxModel {}
 
 export class ProfileImageLightbox implements LightboxModel {