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.json

@@ -158,14 +158,26 @@
     {
       "root": "pages-aigc",
       "pages": [
-        {
-          "path": "home",
-          "style": {
-            "navigationStyle": "custom"
-          }
-        }
-      ]
-    }
+        {
+          "path": "home/home",
+          "style": {
+            "navigationStyle": "custom"
+          }
+        },
+        {
+          "path": "detail/detail",
+          "style": {
+            "navigationStyle": "custom"
+          }
+        },
+        {
+          "path": "record/record",
+          "style": {
+            "navigationStyle": "custom"
+          }
+        }
+      ]
+    }
   ],
   "globalStyle": {
     "navigationBarTextstyle": "black",