chore: seal Design Vision v1 and monorepo scaffold

Archive the differentiated YuXinGu product docs, AI engineering system,
design contract, and Go/Vue scaffold. Next execution prioritizes Cece-parity
over early innovation (see .ai/product/STRATEGY.md).

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/user-h5/src/main.ts

@@ -0,0 +1,8 @@
+import { createApp } from 'vue'
+import { createPinia } from 'pinia'
+import App from './App.vue'
+import router from './router'
+import '@yuxingu/ui/tokens.css'
+import './styles/app.css'
+
+createApp(App).use(createPinia()).use(router).mount('#app')