feat(frontend): connect Next.js server components to Go backend REST API with resilient fallback

- Implement typed REST API client in refer_landing_page/lib/api.ts
- Support API_BASE_URL environment variable with graceful fallback to static content
- Connect Home page (projects, areas, stats), Members page (active, alumni), Publications (highlights, list, patents), Lectures, and Standardization pages to backend endpoints
- Pass all 12 SSG build, TypeScript, ESLint, and E2E quality gates

refer_landing_page/app/publications/_components/CategoryNav.tsx

@@ -1,17 +1,27 @@
 import React from "react";
 import Link from "next/link";
 import { PUB_CATEGORIES } from "../../../content/categories";
-import { publications, patents } from "../../../content/publications";
+import { publications as staticPubs, patents as staticPatents } from "../../../content/publications";
 import { PubCategory } from "../../../content/types";
 
+export interface CategoryCounts {
+  "intl-journal-conf"?: number;
+  "domestic-journal-conf"?: number;
+  patent?: number;
+}
+
 interface CategoryNavProps {
   currentCategory?: PubCategory;
+  counts?: CategoryCounts;
 }
 
-export function CategoryNav({ currentCategory }: CategoryNavProps) {
+export function CategoryNav({ currentCategory, counts }: CategoryNavProps) {
   const getCount = (slug: string) => {
-    if (slug === "patent") return patents.length;
-    return publications.filter((p) => p.category === slug).length;
+    if (counts?.[slug as keyof CategoryCounts] !== undefined) {
+      return counts[slug as keyof CategoryCounts]!;
+    }
+    if (slug === "patent") return staticPatents.length;
+    return staticPubs.filter((p) => p.category === slug).length;
   };
 
   return (