feat: 新增预算后端服务与差旅风险规则库

后端新增预算模型、端点和服务模块，支持预算 CRUD 和余额
查询，清理旧生成规则文件并替换为按严重等级分类的差旅风
险规则库，优化认证权限和报销单访问策略，新增财务规则目
录和演示数据构建脚本，前端预算中心增加对话框交互，完善
审计页面运行时模型和元数据展示，补充单元测试。

web/src/services/api.js

@@ -46,11 +46,13 @@ function readCurrentUserHeaders() {
     const username = String(payload?.username || '').trim()
     const name = String(payload?.name || username).trim()
     const roleCodes = Array.isArray(payload?.roleCodes) ? payload.roleCodes.filter(Boolean) : []
-    const isAdmin = Boolean(payload?.isAdmin)
+    const isAdmin = resolveStoredUserAdminFlag(payload, roleCodes)
     const department = String(payload?.department || payload?.departmentName || '').trim()
+    const costCenter = String(payload?.costCenter || payload?.cost_center || '').trim()
     const safeUsername = pickSafeHeaderValue(username)
     const safeName = pickSafeHeaderValue(name)
     const safeDepartment = pickSafeHeaderValue(department)
+    const safeCostCenter = pickSafeHeaderValue(costCenter)
 
     if (!safeUsername && !safeName) {
       return {}
@@ -73,11 +75,30 @@ function readCurrentUserHeaders() {
       headers['x-auth-department'] = safeDepartment
     }
 
+    if (safeCostCenter) {
+      headers['x-auth-cost-center'] = safeCostCenter
+    }
+
     return headers
   } catch {
     return {}
   }
 }
+
+function resolveStoredUserAdminFlag(payload, roleCodes = []) {
+  const username = String(payload?.username || payload?.account || '').trim().toLowerCase()
+  const role = String(payload?.role || '').trim().toLowerCase()
+  const normalizedRoleCodes = roleCodes.map((item) => String(item || '').trim().toLowerCase()).filter(Boolean)
+
+  return (
+    Boolean(payload?.isAdmin)
+    || username === 'admin'
+    || role === 'admin'
+    || role === '管理员'
+    || role === '系统管理员'
+    || normalizedRoleCodes.includes('admin')
+  )
+}
 
 function normalizeApiBaseUrl(value) {
   return String(value || '/api/v1').replace(/\/$/, '')