chore(proxy): remove CPU/pids limits, add open_file_cache, fix nginx-sync symlink check

deployment/proxy/nginx.conf

@@ -39,6 +39,13 @@ http {
     server_tokens off;
     keepalive_timeout 30s;
 
+    # Gamedata/icons are served from disk by alias locations. Caching the
+    # stat/open results avoids a syscall storm on every room load.
+    open_file_cache max=10000 inactive=30s;
+    open_file_cache_valid 60s;
+    open_file_cache_min_uses 2;
+    open_file_cache_errors off;
+
     client_max_body_size 64m;
     client_body_buffer_size 16k;
     client_header_buffer_size 1k;