feat(P11-P12): 落地治理开关与移动端MVP（G0-G6/H1/M1-M4）

- 新增 Feature Flag 模型、评估服务与管理 API（erp_sync/invoice_verification）\n- 完成 ERP 与验真灰度收口（路由/服务/作业统一判定）\n- 补齐 pay 与手动 sync 的 department_id 灰度上下文\n- 增加管理后台开关页、PWA 基础设施与移动拍照/审批页面\n- 增加回归脚本、安全基线与压测脚本，更新文档与执行合同\n\nIssue: G0,G1,G2,G3,G4,G5,G6,H1,M1,M2,M3,M4

server/src/routes/reimbursements.js

@@ -11,6 +11,7 @@ const {
 const { sendNotificationEmailSafe } = require("../services/email");
 const { enqueueIntegrationEvent } = require("../services/integrations/outbox");
 const { buildErpPayload } = require("../services/integrations/erp");
+const { FEATURE_FLAG_KEYS, evaluateFeatureFlag } = require("../services/featureFlags");
 const {
   buildWorkflowStepsFromApprovalRule,
   resolveActionableStep,
@@ -1691,7 +1692,7 @@ async function reimbursementRoutes(fastify) {
 
       await fastify.prisma.$transaction(async (tx) => {
         const reimbursementRows = await tx.$queryRaw`
-          SELECT id, status, form_number, owner_id, submitter_id,
+          SELECT id, status, form_number, owner_id, submitter_id, department_id,
                  payment_voucher_no, payment_date, payment_channel, paid_at, paid_by
           FROM "reimbursement_forms"
           WHERE id = ${reimbursementId}::uuid
@@ -1772,6 +1773,7 @@ async function reimbursementRoutes(fastify) {
               form_number: true,
               owner_id: true,
               submitter_id: true,
+              department_id: true,
               total_amount: true,
               payment_voucher_no: true,
               payment_date: true,
@@ -1779,14 +1781,40 @@ async function reimbursementRoutes(fastify) {
             },
           });
 
-          if (refreshed && fastify.config.erpSyncEnabled) {
-            await enqueueIntegrationEvent(tx, {
-              eventType: "erp.reimbursement.paid",
-              dedupeKey: refreshed.id,
-              payload: buildErpPayload({ reimbursement: refreshed }),
-              maxAttempts: fastify.config.integrationOutboxMaxAttempts,
-              actorId: request.employee.id,
+          if (refreshed) {
+            const departmentId =
+              refreshed.department_id ?? reimbursement.department_id ?? request.employee.department_id ?? null;
+            const erpGate = await evaluateFeatureFlag({
+              prisma: tx,
+              config: fastify.config,
+              flagKey: FEATURE_FLAG_KEYS.erpSync,
+              departmentId,
+              strictDepartment: true,
             });
+
+            if (erpGate.enabled) {
+              await enqueueIntegrationEvent(tx, {
+                eventType: "erp.reimbursement.paid",
+                dedupeKey: refreshed.id,
+                payload: buildErpPayload({ reimbursement: refreshed }),
+                maxAttempts: fastify.config.integrationOutboxMaxAttempts,
+                actorId: request.employee.id,
+              });
+            } else {
+              await tx.auditLog.create({
+                data: buildAuditLogData(request, {
+                  actorId: request.employee.id,
+                  action: "ERP_SYNC_SKIPPED_BY_FEATURE_FLAG",
+                  targetType: "reimbursement_form",
+                  targetId: refreshed.id,
+                  extra: {
+                    featureFlag: FEATURE_FLAG_KEYS.erpSync,
+                    departmentId,
+                    reason: erpGate.reason,
+                  },
+                }),
+              });
+            }
           }
 
           try {