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/styles/index.scss

@@ -0,0 +1,147 @@
+.template-card {
+  position: relative;
+  flex: 0 0 318px;
+  width: 318px;
+  height: 494px;
+  overflow: hidden;
+  display: flex;
+  flex-direction: column;
+  border-radius: 28px;
+  background: linear-gradient(180deg, #0f7069, #082226);
+  color: #ffffff;
+  text-align: left;
+  box-shadow: 0 18px 34px rgba(24, 37, 50, 0.18);
+  transform: scale(0.96);
+  transform-origin: center;
+  transition: box-shadow 0.18s ease, transform 0.18s ease;
+}
+
+.template-card.is-active {
+  box-shadow: 0 22px 42px rgba(24, 37, 50, 0.2);
+  transform: scale(1);
+}
+
+.template-card.is-postcard .template-copy {
+  background:
+    linear-gradient(180deg, rgba(255, 255, 255, 0.06), rgba(255, 255, 255, 0) 34%),
+    linear-gradient(180deg, #0a4d46, #082226);
+}
+
+.template-card.is-postcard .template-copy::before {
+  background: linear-gradient(180deg, rgba(10, 77, 70, 0), #0a4d46);
+}
+
+.template-media {
+  position: relative;
+  flex: 0 0 358px;
+  height: 358px;
+  overflow: hidden;
+  background: var(--memory-accent);
+}
+
+.template-image {
+  width: 100%;
+  height: 100%;
+  display: block;
+}
+
+.template-media-shade {
+  position: absolute;
+  top: 0;
+  right: 0;
+  bottom: 0;
+  left: 0;
+  background:
+    radial-gradient(92% 45% at 50% 28%, rgba(255, 255, 255, 0.08), rgba(255, 255, 255, 0) 62%),
+    linear-gradient(180deg, rgba(4, 22, 24, 0), rgba(4, 22, 24, 0.02) 58%, rgba(4, 22, 24, 0.24));
+}
+
+.template-copy {
+  position: relative;
+  flex: 0 0 136px;
+  display: flex;
+  flex-direction: column;
+  justify-content: flex-start;
+  align-items: flex-start;
+  padding: 15px 18px 14px;
+  background:
+    linear-gradient(180deg, rgba(255, 255, 255, 0.06), rgba(255, 255, 255, 0) 34%),
+    linear-gradient(180deg, #0f7069, #092128);
+  box-sizing: border-box;
+}
+
+.template-copy::before {
+  content: "";
+  position: absolute;
+  left: 0;
+  right: 0;
+  top: -34px;
+  height: 34px;
+  background: linear-gradient(180deg, rgba(15, 112, 105, 0), #0f7069);
+  pointer-events: none;
+}
+
+.template-badge {
+  position: absolute;
+  top: 14px;
+  right: 18px;
+  height: 24px;
+  display: inline-flex;
+  align-items: center;
+  padding: 0 9px;
+  border-radius: 999px;
+  background: rgba(255, 255, 255, 0.16);
+  color: rgba(255, 255, 255, 0.9);
+  font-size: 10px;
+  line-height: 24px;
+  font-weight: 900;
+}
+
+.template-title {
+  width: 178px;
+  color: #ffffff;
+  font-size: 17px;
+  line-height: 22px;
+  font-weight: 900;
+}
+
+.template-desc {
+  width: 178px;
+  margin-top: 4px;
+  color: rgba(255, 255, 255, 0.76);
+  font-size: 11px;
+  line-height: 15px;
+  font-weight: 800;
+}
+
+.template-note {
+  max-width: 172px;
+  margin-top: 5px;
+  color: rgba(255, 255, 255, 0.86);
+  font-size: 9px;
+  line-height: 13px;
+  font-weight: 900;
+}
+
+.template-select {
+  position: absolute;
+  right: 16px;
+  bottom: 16px;
+  min-width: 108px;
+  height: 40px;
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  margin: 0;
+  padding: 0 16px;
+  border-radius: 999px;
+  background: rgba(255, 255, 255, 0.9);
+  color: #172033;
+  font-size: 13px;
+  line-height: 20px;
+  font-weight: 900;
+}
+
+.template-select::after {
+  border: 0;
+}