feat: increase client_max_body_size to 60M for larger uploads

frontend/nginx.conf

@@ -5,6 +5,11 @@ server {
     root /usr/share/nginx/html;
     index index.html;
 
+    # Allow uploads up to 60 MB (backend limit is 50 MB by default,
+    # configured via MAX_UPLOAD_SIZE_MB; headroom for multipart overhead).
+    # nginx default is 1 MB, which causes 413 errors on large uploads.
+    client_max_body_size 60M;
+
     # ── API proxy ─────────────────────────────────────────────────
     # Container runtime (Docker/Podman) resolves backend:8000 via
     # its built-in DNS.  nginx caches the resolved IP at startup, so