fix: make nginx resolver Podman-compatible

Remove Docker-specific resolver (127.0.0.11) in favor of direct
proxy_pass, which falls back to the system resolver (/etc/resolv.conf).
Mount local nginx.conf into the prod image to override the baked-in config.

docker-compose.prod.yml

@@ -149,6 +149,9 @@ services:
     ports:
       # The only network-facing port. Serves the UI and proxies /api/ to the API.
       - "5173:8080"
+    volumes:
+      # Override the baked-in nginx.conf to use system resolver (Podman-compatible).
+      - ./flowsint-app/nginx.conf:/etc/nginx/nginx.conf:ro
     networks:
       - flowsint_network
     depends_on:

flowsint-app/nginx.conf

@@ -58,13 +58,11 @@ http {
         add_header Referrer-Policy "strict-origin-when-cross-origin" always;
 
         # API reverse proxy — same-origin, no CORS needed.
-        # Expects the API service to be reachable as "api:5001" on the Docker network.
+        # Expects the API service to be reachable as "api:5001" on the compose network.
+        # Uses system resolver (/etc/resolv.conf) — compatible with Docker and Podman.
+        # Trade-off: hostname resolved once at startup; restart app if api IP changes.
         location /api/ {
-            # Resolve at request time via Docker's embedded DNS: survives api
-            # container restarts and lets nginx boot before api is up.
-            resolver 127.0.0.11 valid=10s;
-            set $api_upstream http://api:5001;
-            proxy_pass $api_upstream;
+            proxy_pass http://api:5001;
             proxy_http_version 1.1;
             proxy_set_header Host $host;
             proxy_set_header X-Real-IP $remote_addr;