fix: web API 502 — use Podman-local DNS for gateway proxy

Mount nginx template with NGINX_LOCAL_RESOLVERS and require web→gateway health in deploy checks.

Co-authored-by: Cursor <cursoragent@cursor.com>

web/nginx.conf.template

@@ -0,0 +1,41 @@
+# 请求时解析 gateway（避免启动时 DNS 未就绪导致 emerg）。
+# ${NGINX_LOCAL_RESOLVERS} 由官方入口在 NGINX_ENTRYPOINT_LOCAL_RESOLVERS 开启时从 /etc/resolv.conf 注入。
+resolver ${NGINX_LOCAL_RESOLVERS} valid=10s ipv6=off;
+
+server {
+    listen 80;
+    server_name _;
+    root /usr/share/nginx/html;
+    index index.html;
+
+    location /api/ {
+        set $gw_upstream gateway:8180;
+        proxy_pass http://$gw_upstream;
+        proxy_http_version 1.1;
+        proxy_set_header Host $host;
+        proxy_set_header X-Real-IP $remote_addr;
+        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+        proxy_set_header Authorization $http_authorization;
+        client_max_body_size 64m;
+    }
+
+    location /ai/ {
+        set $gw_upstream gateway:8180;
+        proxy_pass http://$gw_upstream;
+        proxy_http_version 1.1;
+        proxy_set_header Host $host;
+        proxy_set_header Authorization $http_authorization;
+        client_max_body_size 64m;
+    }
+
+    location /gateway/ {
+        set $gw_upstream gateway:8180;
+        proxy_pass http://$gw_upstream;
+        proxy_http_version 1.1;
+        proxy_set_header Host $host;
+    }
+
+    location / {
+        try_files $uri $uri/ /index.html;
+    }
+}