feat(server): 试运行性能索引补强（E9）

- reimbursement_forms/invoice_pool/workflow_tasks/audit_logs 增加常用筛选组合索引
- 仅新增索引与迁移，便于回滚

issues/2026-02-08_21-50-09-p4-trialrun-ready.csv

@@ -7,7 +7,7 @@ E5,报销页精修（列表详情联动）,收敛报销列表详情展示并优
 E6,票据中心精修（OCR与预览）,收敛上传列表详情并强化OCR状态展示绑定与签名预览交互并补data-testid,OCR_PROVIDER=mock联调可轮询pending_ocr且ocr_failed展示原因且预览可用,cd client && npm run typecheck && npm run build,manual,DONE,DONE,DONE,client/src/pages/InvoicePoolPage.tsx | client/src/api/invoicePool.ts | client/src/api/http.ts,"[""E3""]",为E2E补稳定选择器data-testid
 E7,委派管理前端页（运营可用）,新增委派管理页与API封装支持创建列表撤销并加菜单入口与守卫,可创建委派撤销后delegate不可代办且无权限用户403提示正确,"manual: manager创建委派让delegate代办一次后撤销再验证PERM_002",manual,DONE,TODO,TODO,client/src/pages/DelegationsPage.tsx | client/src/api/delegations.ts | client/src/router/index.tsx | client/src/components/navigation/Sidebar.tsx,"[""E3""]",权限码沿用expense.proxy_manage
 E8,默认账号与失败体验收敛,补dev seed默认账号文档并让前端对网络失败给出可操作提示（含“忘记密码请联系管理员重置”）,登录页后端不可达提示服务未启动且README列出默认账号且SYS_001提示可读,"manual: 停后端访问登录页看到提示并按README默认账号登录成功",manual,DONE,TODO,TODO,client/src/pages/LoginPage.tsx | client/src/api/errorMessages.ts | server/README.md | client/README.md,"[""E1""]",仅写dev seed账号不写生产密码与密钥
-E9,DB索引补强（试运行性能）,为列表分页与筛选补组合索引以降低试运行慢查询风险,迁移可重复执行且回归全绿,cd server && npm run prisma:migrate:deploy && ./scripts/regression-all.sh,manual,TODO,TODO,TODO,server/prisma/schema.prisma | server/prisma/migrations/*,"[""E1""]",新增组合索引仅增不破回滚成本低
+E9,DB索引补强（试运行性能）,为列表分页与筛选补组合索引以降低试运行慢查询风险,迁移可重复执行且回归全绿,cd server && npm run prisma:migrate:deploy && ./scripts/regression-all.sh,manual,DONE,TODO,TODO,server/prisma/schema.prisma | server/prisma/migrations/*,"[""E1""]",新增组合索引仅增不破回滚成本低
 E10,后端安全基线（上线级）,增加安全头与关键接口限流并完善上传校验与日志脱敏约定,限流触发行为正确安全头存在上传非法类型被拒绝且不泄露token,"manual: curl压测login并验证429与headers并做一次上传非法类型校验",manual,TODO,TODO,TODO,server/src/app.js | server/src/config.js | server/src/routes/auth.js | server/src/routes/invoicePool.js | server/README.md | server/package.json,"[""E1""]",优先使用@fastify/helmet与@fastify/rate-limit并写回滚说明
 E11,可观测性基线（ready与作业统计）,新增/ready进行DB探活并为OCR与委派回收作业输出结构化统计,ready可反映db状态且作业日志输出claimed updated audited等计数便于排障,"manual: 启动服务curl /ready并触发一次job观察日志字段",manual,TODO,TODO,TODO,server/src/app.js | server/src/jobs/delegationRevokeJob.js | server/src/jobs/ocrJob.js | server/README.md,"[""E10""]",不引入外部监控先提供最小可观测字段
 E12,单域部署（server托管client静态）,支持server托管client dist实现同域cookie并提供开关与SPA回退,开启后通过server根路径访问前端且登录刷新正常,"manual: cd client && npm run build 然后SERVE_CLIENT_DIST=true启动server访问http://127.0.0.1:3000完成登录",manual,TODO,TODO,TODO,server/src/app.js | server/src/config.js | server/README.md | docker-compose.yml,"[""E10""]",优先复用@fastify/static并用正则fallback避开/api

server/prisma/migrations/20260208155029_p4_index_optimizations/migration.sql

@@ -0,0 +1,20 @@
+-- DropIndex
+DROP INDEX "idx_audit_logs_query";
+
+-- CreateIndex
+CREATE INDEX "idx_audit_logs_query" ON "audit_logs"("created_at", "actor_id", "action");
+
+-- CreateIndex
+CREATE INDEX "idx_audit_logs_target_type_created_at" ON "audit_logs"("target_type", "created_at");
+
+-- CreateIndex
+CREATE INDEX "idx_invoice_pool_owner_status_created_at" ON "invoice_pool"("owner_employee_id", "status", "created_at");
+
+-- CreateIndex
+CREATE INDEX "idx_reimbursement_owner_status_updated_at" ON "reimbursement_forms"("owner_id", "status", "updated_at");
+
+-- CreateIndex
+CREATE INDEX "idx_workflow_tasks_status_assignee_id_created_at" ON "workflow_tasks"("status", "assignee_id", "created_at");
+
+-- CreateIndex
+CREATE INDEX "idx_workflow_tasks_status_assignee_role_created_at" ON "workflow_tasks"("status", "assignee_role", "created_at");

server/prisma/schema.prisma

@@ -278,6 +278,7 @@ model AuditLog {
   @@index([request_id])
   @@index([actor_id, created_at])
   @@index([created_at, actor_id, action], map: "idx_audit_logs_query")
+  @@index([target_type, created_at], map: "idx_audit_logs_target_type_created_at")
   @@map("audit_logs")
 }
 
@@ -356,6 +357,7 @@ model ReimbursementForm {
   @@index([paid_by])
   @@index([status])
   @@index([reimbursement_date])
+  @@index([owner_id, status, updated_at], map: "idx_reimbursement_owner_status_updated_at")
   @@map("reimbursement_forms")
 }
 
@@ -459,6 +461,7 @@ model InvoicePool {
   @@index([invoice_code, invoice_number])
   @@index([status])
   @@index([status, ocr_locked_at, created_at], map: "idx_invoice_pool_ocr_queue")
+  @@index([owner_employee_id, status, created_at], map: "idx_invoice_pool_owner_status_created_at")
   @@index([linked_reimbursement_id])
   @@map("invoice_pool")
 }
@@ -543,6 +546,8 @@ model WorkflowTask {
   @@index([assignee_id])
   @@index([assignee_role])
   @@index([status, assignee_id, assignee_role], map: "idx_workflow_tasks_status_assignee")
+  @@index([status, assignee_id, created_at], map: "idx_workflow_tasks_status_assignee_id_created_at")
+  @@index([status, assignee_role, created_at], map: "idx_workflow_tasks_status_assignee_role_created_at")
   @@map("workflow_tasks")
 }