status(host): configure external status page and uptime monitoring host

resources/external/status/docker_compose/compose.yaml.j2

@@ -0,0 +1,36 @@
+# https://gatus.io/
+# https://github.com/TwiN/gatus
+# https://github.com/TwiN/gatus/blob/master/.examples/docker-compose-postgres-storage/compose.yaml
+
+services:
+  database:
+    image: docker.io/library/postgres:18.1
+    volumes:
+      - ./database:/var/lib/postgresql
+    environment:
+      - "POSTGRES_DB=gatus"
+      - "POSTGRES_USER=gatus"
+      - "POSTGRES_PASSWORD={{ secret__gatus_db_password }}"
+    networks:
+      - gatus
+
+  gatus:
+    image: ghcr.io/twin/gatus:v5.34.0
+    restart: always
+    ports:
+      - "8080:8080"
+    environment:
+      - "GATUS_CONFIG_PATH=/config"
+      - "POSTGRES_DB=gatus"
+      - "POSTGRES_USER=gatus"
+      - "POSTGRES_PASSWORD={{ secret__gatus_db_password }}"
+      - "MATRIX_ACCESS_TOKEN={{ secret__gatus_matrix_access_token }}"
+    volumes:
+      - ./configs:/config
+    networks:
+      - gatus
+    depends_on:
+      - database
+
+networks:
+  gatus: