fix: 花名册合同风险统计与风险中心不一致

花名册快捷筛选标签基于当前页数据统计，改为后端返回全局RiskItem统计
- 后端roster API返回globalRiskStats(expiring/expired/unsigned)
- 前端优先使用全局统计，fallback到当前页统计

frontend/src/pages/Roster.tsx

@@ -235,14 +235,17 @@ export default function Roster() {
 
   const hasActiveFilters = search || filterStatus || filterContractStatus || filterDepartment
 
-  /** 计算合同风险统计（基于当前页数据） */
+  /** 全局合同风险统计（来自后端，与风险中心同口径） */
+  const globalRiskStats = rosterData?.globalRiskStats
   const riskStats = useMemo(() => {
+    if (globalRiskStats) return globalRiskStats
+    // fallback: 当前页统计
     const expiring = employees.filter((e: any) => e.contractStatus === 'expiring').length
     const expired = employees.filter((e: any) => e.contractStatus === 'expired').length
     const unsigned = employees.filter((e: any) => ['unsigned', 'unsigned_over_30', 'unsigned_over_year'].includes(e.contractStatus)).length
     const probation = employees.filter((e: any) => e.probationInfo?.isProbation && e.probationInfo?.isExpiring).length
     return { expiring, expired, unsigned, probation }
-  }, [employees])
+  }, [globalRiskStats, employees])
 
   /** 快捷筛选标签 */
   const quickFilters = [