feat(image): simplify generation and release 1.2.0

plugins/design-md/.codex-plugin/plugin.json

@@ -1,6 +1,6 @@
 {
   "name": "design-md",
-  "version": "1.1.0",
+  "version": "1.2.0",
   "description": "创建或完善 DESIGN.md，维护项目设计读取入口，并应用、核对界面设计规则。",
   "author": {
     "name": "EAPIL",