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-lock.json

@@ -1,15 +1,15 @@
 {
   "name": "iflow-engine",
-  "version": "1.1.3",
+  "version": "1.1.8",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "iflow-engine",
-      "version": "1.1.3",
+      "version": "1.1.8",
       "license": "MIT",
       "dependencies": {
-        "iflow-engine-base": "^1.1.5",
+        "iflow-engine-base": "^2.0.0",
         "three": "^0.182.0"
       },
       "devDependencies": {
@@ -1431,6 +1431,12 @@
         "node": ">=0.3.1"
       }
     },
+    "node_modules/draco3d": {
+      "version": "1.5.7",
+      "resolved": "https://registry.npmjs.org/draco3d/-/draco3d-1.5.7.tgz",
+      "integrity": "sha512-m6WCKt/erDXcw+70IJXnG7M3awwQPAsZvJGX5zY7beBqpELw6RDGkYVU0W43AFxye4pDZ5i2Lbyc/NNGqwjUVQ==",
+      "license": "Apache-2.0"
+    },
     "node_modules/dunder-proto": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/dunder-proto/-/dunder-proto-1.0.1.tgz",
@@ -1781,13 +1787,14 @@
       }
     },
     "node_modules/iflow-engine-base": {
-      "version": "1.1.5",
-      "resolved": "https://registry.npmjs.org/iflow-engine-base/-/iflow-engine-base-1.1.5.tgz",
-      "integrity": "sha512-7i5igYpnsmmf9LyuzmyufAB70Gl9eHrjRpuEmsOpVNXovun4NTCeOR7e9hus9liETjGlVKhkyq26qomVq3ytew==",
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/iflow-engine-base/-/iflow-engine-base-2.0.0.tgz",
+      "integrity": "sha512-G4GyGikgHLtvf9nCjJD7eG8+2kDFFFavSMLCUOux+2Vw5BMNzj1R3w2/mgasUYY2ou6zL8j59j6xcFm0E+7xRw==",
       "license": "ISC",
       "dependencies": {
         "@types/three": "^0.181.0",
         "axios": "^1.13.2",
+        "draco3d": "^1.5.7",
         "jszip": "^3.10.1",
         "stats.js": "^0.17.0",
         "three": "^0.181.2",