docs: add NPM forward auth config for reference

Config for home.schweitz.net with Authentik forward auth:
- Static assets excluded via auth_request off
- Proper proxy pass to upstream

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

npm-config.conf

@@ -0,0 +1,53 @@
+# Increase buffer size for large headers from Authentik
+proxy_buffers 8 16k;
+proxy_buffer_size 32k;
+
+# Exclude static assets from forward auth
+# These paths bypass auth_request but still proxy to upstream
+location ~ ^/(manifest\.json|favicon\.(ico|png)|health|icons|assets) {
+    auth_request off;
+    proxy_pass $forward_scheme://$server:$port;
+}
+
+# Forward authentication via standalone outpost
+auth_request /outpost.goauthentik.io/auth/nginx;
+error_page 401 = @goauthentik_proxy_signin;
+
+# Capture auth response headers
+auth_request_set $auth_cookie $upstream_http_set_cookie;
+auth_request_set $authentik_username $upstream_http_x_authentik_username;
+auth_request_set $authentik_groups $upstream_http_x_authentik_groups;
+auth_request_set $authentik_email $upstream_http_x_authentik_email;
+auth_request_set $authentik_name $upstream_http_x_authentik_name;
+auth_request_set $authentik_uid $upstream_http_x_authentik_uid;
+
+# Forward auth headers to application
+add_header Set-Cookie $auth_cookie;
+proxy_set_header X-authentik-username $authentik_username;
+proxy_set_header X-authentik-groups $authentik_groups;
+proxy_set_header X-authentik-email $authentik_email;
+proxy_set_header X-authentik-name $authentik_name;
+proxy_set_header X-authentik-uid $authentik_uid;
+
+# Outpost proxy location
+location /outpost.goauthentik.io {
+    proxy_pass https://localhost:9444/outpost.goauthentik.io;
+    proxy_set_header Host $host;
+    proxy_set_header X-Original-URL $scheme://$http_host$request_uri;
+    proxy_set_header X-Forwarded-Proto $scheme;
+    proxy_set_header X-Forwarded-Host $http_host;
+    proxy_set_header X-Forwarded-For $remote_addr;
+    proxy_pass_request_body off;
+    proxy_set_header Content-Length "";
+
+    # WebSocket support
+    proxy_http_version 1.1;
+    proxy_set_header Upgrade $http_upgrade;
+    proxy_set_header Connection $connection_upgrade;
+}
+
+# Signin redirect handler
+location @goauthentik_proxy_signin {
+    internal;
+    return 302 /outpost.goauthentik.io/start?rd=$request_uri;
+}