Run on the nodesandbox runtime: harness toolchain, Hono server entry

The sandbox loads Vite's native tools as WASI (NAPI_RS_FORCE_WASI=error)
and only ships glue for rolldown 1.1.x. Vite 8.3 pulls rolldown 1.2.x,
whose binding needs emnapi 2.0 alpha, so boot failed with 'WASI binding
not found'. Match the runtime-host harness TanStack sample instead:

- Pin vite 8.1.3, rolldown + @rolldown/binding-wasm32-wasi 1.1.4,
  @vitejs/plugin-react 6.0.0, tailwindcss + @tailwindcss/vite 4.3.1
  (exact versions: the sandbox resolves package.json, not yarn.lock)
- Drop Nitro (it brings rolldown 1.2.x) and the Vercel config
- Hono now sits in src/server.ts, Start's server entry, routing /api/*
  ahead of start.fetch, as in the harness
- dev runs 'vite dev --host 0.0.0.0 --port 3000'; config is .mjs
- Await product recommendations in the loader to fix a hydration
  mismatch between the SSR skeleton and the settled client render

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

vite.config.mjs

@@ -0,0 +1,27 @@
+import { defineConfig } from 'vite';
+import { tanstackStart } from '@tanstack/react-start/plugin/vite';
+import react from '@vitejs/plugin-react';
+import tailwindcss from '@tailwindcss/vite';
+import { fileURLToPath, URL } from 'node:url';
+
+// Absolute origin for canonical and Open Graph URLs. Inlined at build time so
+// the server render and the client agree on it; set VITE_SITE_URL in production.
+const siteUrl = process.env.VITE_SITE_URL ?? 'http://localhost:3000';
+
+export default defineConfig({
+  server: { port: 3000 },
+  plugins: [
+    // Start must come before the React plugin.
+    tanstackStart(),
+    react(),
+    tailwindcss(),
+  ],
+  define: {
+    'import.meta.env.VITE_SITE_URL': JSON.stringify(siteUrl),
+  },
+  resolve: {
+    alias: {
+      '@': fileURLToPath(new URL('./src', import.meta.url)),
+    },
+  },
+});