refactor: split project into web and server directories

- Move frontend to web/ directory
- Add server/ directory for backend
- Restructure project for前后端分离架构

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

web/src/data/policies.js

@@ -0,0 +1,5 @@
+export const policies = [
+  { code: 'A1', title: '差旅住宿标准', note: '按城市、职级、会议峰值期动态判断。', badge: '启用', tone: 'success' },
+  { code: 'A2', title: '发票查重与验真', note: '票号、税号、金额、抬头四重校验。', badge: '启用', tone: 'success' },
+  { code: 'A3', title: '业务招待材料前置', note: '客户名单、拜访纪要、审批单缺一不可。', badge: '建议强化', tone: 'warning' }
+]