fix: 退回报销支持留痕删除（09-04-reimbursement-state-gap-finance-view）

server/prisma/migrations/20260910010000_reimbursement_retained_delete/migration.sql

@@ -0,0 +1,10 @@
+ALTER TABLE "reimbursement_forms"
+  ADD COLUMN "deleted_at" TIMESTAMP(3),
+  ADD COLUMN "deleted_by" UUID,
+  ADD CONSTRAINT "reimbursement_forms_deleted_by_fkey"
+    FOREIGN KEY ("deleted_by") REFERENCES "employees"("id") ON DELETE RESTRICT ON UPDATE CASCADE,
+  ADD CONSTRAINT "reimbursement_forms_deleted_state_check"
+    CHECK (("deleted_at" IS NULL AND "deleted_by" IS NULL)
+      OR ("deleted_at" IS NOT NULL AND "deleted_by" IS NOT NULL AND "status" = 'cancelled'));
+
+CREATE INDEX "idx_reimbursement_forms_deleted_at" ON "reimbursement_forms"("deleted_at");