feat: Add presence heartbeat for Matrix online status

- matrix-gateway: POST /internal/matrix/presence/online endpoint
- usePresenceHeartbeat hook with activity tracking
- Auto away after 5 min inactivity
- Offline on page close/visibility change
- Integrated in MatrixChatRoom component

nginx/api-gateway.conf

@@ -0,0 +1,80 @@
+events {
+    worker_connections 1024;
+}
+
+http {
+    upstream city_service {
+        server city-service:7001;
+    }
+
+    upstream space_service {
+        server space-service:7002;
+    }
+
+    server {
+        listen 80;
+        server_name localhost;
+
+        # Health check
+        location /health {
+            return 200 "API Gateway OK\n";
+            add_header Content-Type text/plain;
+        }
+
+        # City API
+        location /api/city/ {
+            proxy_pass http://city_service/api/city/;
+            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 $scheme;
+            
+            # CORS
+            add_header 'Access-Control-Allow-Origin' '*' always;
+            add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS' always;
+            add_header 'Access-Control-Allow-Headers' 'DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range' always;
+            
+            if ($request_method = 'OPTIONS') {
+                add_header 'Access-Control-Max-Age' 1728000;
+                add_header 'Content-Type' 'text/plain; charset=utf-8';
+                add_header 'Content-Length' 0;
+                return 204;
+            }
+        }
+
+        # Space API
+        location /space/ {
+            proxy_pass http://space_service/space/;
+            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 $scheme;
+            
+            # CORS
+            add_header 'Access-Control-Allow-Origin' '*' always;
+            add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS' always;
+            add_header 'Access-Control-Allow-Headers' 'DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range' always;
+            
+            if ($request_method = 'OPTIONS') {
+                add_header 'Access-Control-Max-Age' 1728000;
+                add_header 'Content-Type' 'text/plain; charset=utf-8';
+                add_header 'Content-Length' 0;
+                return 204;
+            }
+        }
+
+        # City Service Health
+        location /health/city {
+            proxy_pass http://city_service/health;
+        }
+
+        # Space Service Health
+        location /health/space {
+            proxy_pass http://space_service/health;
+        }
+    }
+}
+
+
+
+