feat: upgrade to v1.2.0 with model param validation and UI improvements

- Upgrade iflow-engine-base to ^2.0.0
- Add sanitizeModelParams for robust model operation validation
- Add try-catch error handling for render mode and model tool calls
- Preserve tree scroll position across tab switches
- Optimize tree node reveal with visibility check and centered scrolling
- Refactor collectModelParams to support multi-model grouping
- Fix tree CSS: remove duplicates, constrain overflow, improve layout
- Move version label to bottom-left
- Rebuild demo libs

package.json

@@ -1,6 +1,6 @@
 {
   "name": "iflow-engine",
-  "version": "1.1.7",
+  "version": "1.2.0",
   "description": "iFlow Engine SDK for Vue2, Vue3, React and HTML",
   "main": "./dist/iflow-engine.umd.js",
   "module": "./dist/iflow-engine.es.js",
@@ -19,7 +19,7 @@
     "dev": "vite",
     "build": "tsc && vite build",
     "copy:demo": "mkdir -p demo/lib && cp dist/iflow-engine.es.js dist/iflow-engine.umd.js dist/iflow-engine.umd.js.map demo/lib/",
-    "copy:demo-draco": "mkdir -p demo/static/js/draco && cp node_modules/iflow-engine-base/dist/draco/*.js node_modules/iflow-engine-base/dist/draco/*.wasm demo/static/js/draco/",
+    "copy:demo-draco": "mkdir -p demo/static/js/draco && (cp node_modules/iflow-engine-base/dist/draco/*.js demo/static/js/draco/ 2>/dev/null || true) && (cp node_modules/iflow-engine-base/dist/draco/*.wasm demo/static/js/draco/ 2>/dev/null || true)",
     "copy:demo-all": "npm run copy:demo && npm run copy:demo-draco",
     "copy:demo-vue": "mkdir -p demo-vue/public/lib && cp dist/iflow-engine.es.js dist/iflow-engine.umd.js dist/iflow-engine.umd.js.map demo-vue/public/lib/",
     "dev:demo": "npm run build && npm run copy:demo-all && cd demo && npm run dev",
@@ -59,7 +59,7 @@
     "vite-plugin-dts": "^4.5.4"
   },
   "dependencies": {
-    "iflow-engine-base": "^1.1.5",
+    "iflow-engine-base": "^2.0.0",
     "three": "^0.182.0"
   }
-}
+}