fix: harden request and task security

src/main/resources/sql/init-auth-schema.sql

@@ -5,6 +5,22 @@
 
 USE `demo`;
 
+SET @need_uk_username = (
+    SELECT CASE WHEN COUNT(1) = 0 THEN 1 ELSE 0 END
+    FROM information_schema.statistics
+    WHERE table_schema = DATABASE()
+      AND table_name = 'sys_user'
+      AND index_name = 'uk_username'
+);
+SET @sql_uk_username = IF(
+    @need_uk_username = 1,
+    'ALTER TABLE `sys_user` ADD UNIQUE KEY `uk_username` (`username`)',
+    'SELECT 1'
+);
+PREPARE stmt_uk_username FROM @sql_uk_username;
+EXECUTE stmt_uk_username;
+DEALLOCATE PREPARE stmt_uk_username;
+
 CREATE TABLE IF NOT EXISTS `sys_role` (
     `id`           BIGINT       NOT NULL COMMENT '主键ID',
     `role_code`    VARCHAR(64)  NOT NULL COMMENT '角色编码',