Add stack Update, ComfyUI model manager, and slim ComfyUI stack.

Server UI gains Update on stack cards, ComfyUI Models tab with workflow
scan and downloads, and centralized comfyui_config. Model catalog and
download scripts move from stacks/comfyui to server-ui so ComfyUI stays a
minimal Docker wrapper for easier image updates.

stacks/server-ui/scripts/comfyui/list-models.sh

@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+
+# shellcheck disable=SC1091
+source "${SCRIPT_DIR}/catalog-lib.sh"
+
+load_comfyui_stack_env
+
+DATA_ROOT="${DATA_ROOT:-/data}"
+catalog_ensure_dirs "${DATA_ROOT}"
+
+echo "=== ComfyUI model catalog ==="
+echo "Catalog: ${CATALOG_FILE}"
+echo "Data:    ${DATA_ROOT}"
+echo ""
+
+printf "%-24s %-12s %-8s %s\n" "ID" "CATEGORY" "ON DISK" "NAME"
+printf "%-24s %-12s %-8s %s\n" "----" "--------" "-------" "----"
+
+while IFS= read -r model_id; do
+  name="$(catalog_get_field "${model_id}" name)"
+  category="$(catalog_get_field "${model_id}" category)"
+  if catalog_model_downloaded "${model_id}"; then
+    on_disk="yes"
+  else
+    on_disk="no"
+  fi
+  printf "%-24s %-12s %-8s %s\n" "${model_id}" "${category}" "${on_disk}" "${name}"
+done < <(catalog_list_ids)
+
+echo ""
+echo "Download on demand: ${SCRIPT_DIR}/download-model.sh <id>"
+echo "Target root:        ${DATA_ROOT}/apps/comfyui/models/"