fix(web-admin): polyfill Buffer/global for contract Word export in Vite

html-to-docx still reads Node globals after Vite rebundles; inject buffer polyfill, map global to globalThis, and alias the package to the browser build.

Co-authored-by: Cursor <cursoragent@cursor.com>

web-admin/package.json

@@ -67,6 +67,7 @@
     "@wangeditor/editor": "^5.1.23",
     "@wangeditor/editor-for-vue": "next",
     "axios": "^1.12.2",
+    "buffer": "^6.0.3",
     "crypto-js": "^4.2.0",
     "dagre": "^0.8.5",
     "echarts": "^6.0.0",