feat(website): 官网企业版视觉升级

- 引入 Geist 字体，去除紫色渐变，克制阴影与交互态
- 导航/卡片/按钮统一企业风格，各区块视觉收敛

website/package.json

@@ -10,6 +10,7 @@
   },
   "dependencies": {
     "@fontsource/fira-code": "^5.3.0",
+    "@fontsource/geist": "^5.3.0",
     "@fontsource/inter": "^5.3.0",
     "@phosphor-icons/react": "^2.1.10",
     "react": "^18.3.1",