fix: nginx proxy timeout for long SSH/WinRM agent actions (0.20.3)

Raise proxy_read_timeout to 960s for agent-update and related API paths so bootstrap git clone does not hit 504 from nginx.

deploy/nginx/sac.conf.example

@@ -31,6 +31,19 @@ server {
 
     client_max_body_size 2m;
 
+    # SSH/WinRM и git-probe: backend ждёт до 900s
+    location ~ ^/api/v1/(hosts/[0-9]+/actions/(agent-update|agent-update-fallback|ssh-test|winrm-test)|settings/agent-updates/test-git) {
+        proxy_pass http://sac_api;
+        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 X-Forwarded-Proto $scheme;
+        proxy_connect_timeout 30s;
+        proxy_send_timeout 960s;
+        proxy_read_timeout 960s;
+    }
+
     location / {
         proxy_pass http://sac_api;
         proxy_http_version 1.1;