feat(frontend): purge all static content fallback files and enforce strict backend-only dynamic rendering

- Delete all legacy static content data files (members.ts, publications.ts, lectures.ts, standards.ts, projects.ts)
- Remove all fallback imports and static fallbacks across all page components
- Enforce strict dynamic runtime fetching where pages render empty datasets when Go backend server is unavailable

refer_landing_page/app/lectures/page.tsx

@@ -1,6 +1,5 @@
 import React from "react";
 import type { Metadata } from "next";
-import { semesters as staticSemesters } from "../../content/lectures";
 import { getSemesters } from "../../lib/api";
 
 export const metadata: Metadata = {
@@ -11,7 +10,7 @@ export const metadata: Metadata = {
 export const dynamic = "force-dynamic";
 
 export default async function LecturesPage() {
-  const semesters = (await getSemesters()) ?? staticSemesters;
+  const semesters = (await getSemesters()) ?? [];
 
   const recentSemesters = semesters.slice(0, 3);
   const olderSemesters = semesters.slice(3);