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/ResultPreview/index.vue

@@ -0,0 +1,25 @@
+<template>
+  <view class="result-preview" :style="{ '--result-accent': result.accent }">
+    <image class="result-preview-image" :src="result.cover" mode="aspectFill" />
+    <view class="result-preview-shade" />
+
+    <view class="result-preview-caption">
+      <text class="result-preview-badge">{{ result.variantLabel }}</text>
+      <text class="result-preview-title">{{ result.title }}</text>
+      <text class="result-preview-desc">{{ result.desc }}</text>
+    </view>
+  </view>
+</template>
+
+<script setup>
+defineProps({
+  result: {
+    type: Object,
+    default: () => ({}),
+  },
+});
+</script>
+
+<style scoped lang="scss">
+@import "./styles/index.scss";
+</style>

src/pages-aigc/detail/components/ResultPreview/styles/index.scss

@@ -0,0 +1,79 @@
+.result-preview {
+  position: relative;
+  height: 360px;
+  overflow: hidden;
+  border-radius: 26px;
+  background: var(--result-accent, #0a4d46);
+  color: #ffffff;
+  box-shadow: 0 18px 34px rgba(17, 35, 49, 0.12);
+}
+
+.result-preview-image {
+  position: absolute;
+  top: 0;
+  right: 0;
+  bottom: 0;
+  left: 0;
+  width: 100%;
+  height: 100%;
+  display: block;
+}
+
+.result-preview-shade {
+  position: absolute;
+  top: 0;
+  right: 0;
+  bottom: 0;
+  left: 0;
+  background: linear-gradient(
+    180deg,
+    rgba(0, 0, 0, 0.02) 0%,
+    rgba(0, 0, 0, 0.16) 48%,
+    rgba(0, 0, 0, 0.74) 100%
+  );
+}
+
+.result-preview-caption {
+  position: absolute;
+  right: 18px;
+  bottom: 18px;
+  left: 18px;
+}
+
+.result-preview-badge {
+  height: 20px;
+  display: inline-flex;
+  align-items: center;
+  padding: 0 8px;
+  border-radius: 999px;
+  background: rgba(255, 255, 255, 0.2);
+  color: #ffffff;
+  font-size: 9px;
+  line-height: 20px;
+  font-weight: 900;
+  letter-spacing: 0.7px;
+}
+
+.result-preview-title,
+.result-preview-desc {
+  display: block;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+.result-preview-title {
+  margin-top: 12px;
+  color: #ffffff;
+  font-size: 23px;
+  line-height: 30px;
+  font-weight: 900;
+}
+
+.result-preview-desc {
+  margin-top: 6px;
+  color: rgba(255, 255, 255, 0.78);
+  font-size: 12px;
+  line-height: 18px;
+  font-weight: 800;
+}