chore: stub educationService to fix broken build

Add a minimal educationService stub that returns empty data,
unblocking the build before the SUMI design system migration.

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/web/src/services/educationService.ts

@@ -0,0 +1,12 @@
+/**
+ * Education Service — Stub
+ * TODO: Implement with real API when education backend is ready
+ */
+import type { Course } from '@/types';
+
+export const educationService = {
+  async getCatalog(): Promise<Course[]> {
+    // Stub — returns empty array until backend endpoint is available
+    return [];
+  },
+};