feat(aigc): add travel postcard AIGC feature

Add complete travel postcard AIGC creation workflow including:
- New AIGC pages: template selection home, result detail, and history records
- Reusable UI components: template card, flow steps, result preview, action buttons, record lists
- Static assets including template images, fonts and styles
- Updated TopNavBar component to support menu button alignment
- Register new AIGC page routes in pages.json
- Add mock data for templates, user records and result details

src/pages-aigc/detail/components/ResultMeta/index.vue

@@ -0,0 +1,21 @@
+<template>
+  <view class="result-meta">
+    <view v-for="item in items" :key="item.label" class="result-meta-item">
+      <text class="result-meta-label">{{ item.label }}</text>
+      <text class="result-meta-value">{{ item.value }}</text>
+    </view>
+  </view>
+</template>
+
+<script setup>
+defineProps({
+  items: {
+    type: Array,
+    default: () => [],
+  },
+});
+</script>
+
+<style scoped lang="scss">
+@import "./styles/index.scss";
+</style>