feat(21-05): enable route-based code splitting via TanStack Router autoCodeSplitting

Enable autoCodeSplitting in TanStackRouterVite plugin to split the monolithic
582 KB bundle into route-level chunks. Main vendor chunk drops to 454 KB with
initiative detail (~13 KB), inbox (~13 KB), and dashboard (~65 KB) as separate
lazy-loaded chunks. Eliminates the Vite 500 KB chunk size warning.

packages/web/vite.config.ts

@@ -4,7 +4,7 @@ import { TanStackRouterVite } from "@tanstack/router-plugin/vite";
 import react from "@vitejs/plugin-react";
 
 export default defineConfig({
-  plugins: [TanStackRouterVite(), react()],
+  plugins: [TanStackRouterVite({ autoCodeSplitting: true }), react()],
   resolve: {
     alias: {
       "@": path.resolve(__dirname, "./src"),