Include app.html in build.

vite.config.ts

@@ -1,4 +1,5 @@
 import { defineConfig } from 'vite';
+import { resolve } from 'path';
 
 export default defineConfig({
   root: 'web',
@@ -6,5 +7,12 @@ export default defineConfig({
   build: {
     outDir: '../dist',
     emptyOutDir: true,
+    rollupOptions: {
+      input: {
+        index: resolve(__dirname, 'web/index.html'),
+        app: resolve(__dirname, 'web/app.html'),
+      },
+    },
   },
 });
+