fix: add client_max_body_size 200m to nginx API proxy

Nginx defaults to 1MB body size, causing 413 on JAR uploads through
the UI proxy. Matches the Spring Boot multipart limit.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/nginx.conf

@@ -12,6 +12,7 @@ server {
     # API proxy — target set via CAMELEER_API_URL env var (default: http://cameleer3-server:8081)
     location /api/ {
         proxy_pass         ${CAMELEER_API_URL};
+        client_max_body_size 200m;
         proxy_set_header   Host $host;
         proxy_set_header   X-Real-IP $remote_addr;
         proxy_set_header   X-Forwarded-For $proxy_add_x_forwarded_for;