Fix: Use same-origin API for HuggingFace Spaces

frontend/src/lib/api.ts

@@ -1,4 +1,4 @@
-const API_BASE = 'http://localhost:8000';
+const API_BASE = typeof window !== 'undefined' && window.location.hostname === 'localhost' ? 'http://localhost:8000' : '';
 
 export interface ClassificationResult {
   label: string;