feat(content): add founding history page for the alumni association

This commit introduces a new page detailing the founding history of the alumni association.

- Adds the new page at `/about/founded-history` which includes the origin story, organizational structure, and a list of donors for the clubhouse.
- Restructures the `/about` route by moving the existing page to `/about/index` to accommodate nested pages.
- Updates the main navigation menu to include a dropdown link to the new 'Founding History' page.
- Adds a link to the old alumni website under 'Friendly Links' for historical reference.

app/layouts/default.vue

@@ -125,6 +125,14 @@ const items = computed<NavigationMenuItem[]>(() => [
     label: "关于校友会",
     to: "/about",
     active: route.path.startsWith("/about"),
+    children: [
+      {
+        label: "创会简史",
+        to: "/about/founded-history",
+        active: route.path.startsWith("/about/founded-history"),
+        icon: "mdi:history",
+      },
+    ],
   },
   {
     label: "友情链接",
@@ -147,6 +155,12 @@ const items = computed<NavigationMenuItem[]>(() => [
         to: "https://www.dongzong.my/",
         target: "_blank",
       },
+      {
+        label: "永中校友网 - 旧站",
+        icon: "mdi:web-clock",
+        to: "https://vtour.my/yphsalumni/",
+        target: "_blank",
+      },
     ],
   },
   // { label: "捐赠", to: "#donate", active: route.path.startsWith("#donate") },