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/home/components/TemplateCard/index.vue

@@ -0,0 +1,44 @@
+<template>
+  <view
+    class="template-card"
+    :class="[
+      active ? 'is-active' : '',
+      template.tone ? `is-${template.tone}` : '',
+    ]"
+    :style="{ '--memory-accent': template.accent || '#0f7069' }"
+  >
+    <view class="template-media">
+      <image class="template-image" :src="template.cover" mode="aspectFill" />
+      <view class="template-media-shade" />
+    </view>
+
+    <view class="template-copy">
+      <text class="template-badge">{{ template.badge }}</text>
+      <text class="template-title ellipsis-1">{{ template.title }}</text>
+      <text class="template-desc ellipsis-1">{{ template.desc }}</text>
+      <text class="template-note ellipsis-1">{{ template.note }}</text>
+      <button class="template-select" type="default" @tap.stop="emit('select')">
+        {{ template.buttonText }}
+      </button>
+    </view>
+  </view>
+</template>
+
+<script setup>
+defineProps({
+  template: {
+    type: Object,
+    default: () => ({}),
+  },
+  active: {
+    type: Boolean,
+    default: false,
+  },
+});
+
+const emit = defineEmits(["select"]);
+</script>
+
+<style scoped lang="scss">
+@import "./styles/index.scss";
+</style>