支持企微通讯录缺失手机号（07-26-internal-ops-recovery-baseline）

server/prisma/migrations/20260727153000_allow_employee_phone_null/migration.sql

@@ -0,0 +1,5 @@
+-- Enterprise WeChat directory exports may omit a member phone number.
+-- PostgreSQL unique constraints continue to reject duplicate non-null phones
+-- while allowing multiple employees to remain temporarily unfilled.
+ALTER TABLE "employees"
+  ALTER COLUMN "phone" DROP NOT NULL;