fix: update routing to show online board at /, fix component tests

- Changed root route (/) to show OnlineBoardStartPage directly instead of redirecting
- Updated component tests to visit /components route
- Fixed button component test assertions (CSS checks and disabled state verification)

apps/react/src/app/router/routes.tsx

@@ -1,12 +1,17 @@
 import { Navigate, RouteObject } from 'react-router-dom'
 
 const routes: RouteObject[] = [
-  // Root redirect to onlineboard
+  // Root shows OnlineBoardStartPage
   {
     path: '/',
-    element: <Navigate to="/onlineboard" replace />,
+    lazy: async () => {
+      const { OnlineBoardStartPage } = await import(
+        '../pages/OnlineBoardStartPage'
+      )
+      return { Component: OnlineBoardStartPage }
+    },
   },
-  // Online Board routes
+  // Online Board routes (alias for backward compatibility)
   {
     path: '/onlineboard',
     lazy: async () => {