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

server/prisma/schema.prisma

@@ -578,7 +578,7 @@ model Employee {
   id                        String                    @id @default(uuid()) @db.Uuid
   employee_no               String                    @unique @default(dbgenerated("generate_employee_number()"))
   name                      String
-  phone                     String                    @unique
+  phone                     String?                   @unique
   email                     String                    @unique
   department_id             String                    @db.Uuid
   legal_entity_id           String?                   @db.Uuid