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/components/TabBar.vue

@@ -0,0 +1,53 @@
+<template>
+  <nav class="tabbar" aria-label="主导航">
+    <router-link
+      v-for="item in items"
+      :key="item.to"
+      :to="item.to"
+      class="item"
+      :class="{ ask: item.ask, on: isActive(item.to) }"
+    >
+      <span class="ni">{{ item.icon }}</span>
+      {{ item.label }}
+    </router-link>
+  </nav>
+</template>
+
+<script setup lang="ts">
+import { useRoute } from 'vue-router'
+
+const route = useRoute()
+const items = [
+  { to: '/', icon: '⌂', label: '首页' },
+  { to: '/explore', icon: '◎', label: '探索' },
+  { to: '/ask', icon: '问', label: '问', ask: true },
+  { to: '/companion', icon: '♡', label: '陪伴' },
+  { to: '/mine', icon: '◍', label: '我的' },
+]
+
+function isActive(to: string): boolean {
+  if (to === '/') return route.path === '/'
+  return route.path.startsWith(to)
+}
+</script>
+
+<style scoped>
+.tabbar{
+  position:fixed;bottom:0;left:50%;transform:translateX(-50%);
+  width:100%;max-width:var(--yxg-max-w);background:#fff;
+  display:flex;justify-content:space-around;
+  padding:6px 0 calc(10px + env(safe-area-inset-bottom,0));
+  border-top:1px solid #f0f0f0;z-index:100;
+}
+.item{
+  flex:1;display:flex;flex-direction:column;align-items:center;gap:2px;
+  font-size:10px;color:var(--yxg-sub);padding:2px 0;
+}
+.item.on{color:var(--yxg-pri);font-weight:600}
+.ni{font-size:16px;line-height:1.2}
+.item.ask .ni{
+  width:36px;height:36px;border-radius:50%;background:var(--yxg-pri);color:#fff;
+  display:flex;align-items:center;justify-content:center;font-size:14px;margin-top:-10px;
+}
+.item.ask.on{color:var(--yxg-pri)}
+</style>