Add ClickHouse CT template and installer

Introduce ClickHouse support by adding a container template (ct/clickhouse.sh), an installer script (install/clickhouse-install.sh) and app metadata (json/clickhouse.json). The installer configures ClickHouse to listen on 0.0.0.0, restarts the service, and performs OS update, networking checks, MOTD/customization and cleanup. Metadata declares default resources (2 CPU, 4GB RAM, 10GB disk), interface port 8123, documentation/website links, and a warning about the default user having no password.

ct/clickhouse.sh

@@ -0,0 +1,43 @@
+#!/usr/bin/env bash
+source <(curl -fsSL https://raw.githubusercontent.com/community-scripts/ProxmoxVED/main/misc/build.func)
+# Copyright (c) 2021-2026 community-scripts ORG
+# Author: community-scripts ORG
+# License: MIT | https://github.com/community-scripts/ProxmoxVED/raw/main/LICENSE
+# Source: https://clickhouse.com
+
+APP="ClickHouse"
+var_tags="${var_tags:-database;analytics}"
+var_cpu="${var_cpu:-2}"
+var_ram="${var_ram:-4096}"
+var_disk="${var_disk:-10}"
+var_os="${var_os:-debian}"
+var_version="${var_version:-13}"
+var_unprivileged="${var_unprivileged:-1}"
+
+header_info "$APP"
+variables
+color
+catch_errors
+
+function update_script() {
+  header_info
+  check_container_storage
+  check_container_resources
+
+  if ! command -v clickhouse-server &>/dev/null; then
+    msg_error "No ${APP} Installation Found!"
+    exit
+  fi
+
+  setup_clickhouse
+  exit
+}
+
+start
+build_container
+description
+
+msg_ok "Completed Successfully!\n"
+echo -e "${CREATING}${GN}${APP} setup has been successfully initialized!${CL}"
+echo -e "${INFO}${YW} Access it using the following URL:${CL}"
+echo -e "${TAB}${GATEWAY}${BGN}http://${IP}:8123${CL}"