feat: restore learning feedback and knowledge capabilities

backend/script/sql/aihr_practice_mysql8.sql

@@ -119,6 +119,8 @@ CREATE TABLE IF NOT EXISTS `aihr_practice_assignment` (
   `source` varchar(30) NOT NULL DEFAULT 'manual' COMMENT '来源 daily/camp/retry/manual',
   `reason` varchar(500) DEFAULT NULL COMMENT '派发原因',
   `status` varchar(30) NOT NULL DEFAULT '待训练' COMMENT '状态',
+  `due_date` date DEFAULT NULL COMMENT '训练截止日期',
+  `request_key` varchar(100) DEFAULT NULL COMMENT '客户端幂等请求ID',
   `answer_text` varchar(1000) DEFAULT NULL COMMENT '每日三题作答',
   `answer_audio_url` varchar(500) DEFAULT NULL COMMENT '每日三题语音回放地址',
   `answer_audio_oss_id` bigint DEFAULT NULL COMMENT '每日三题语音OSS编号',
@@ -130,6 +132,7 @@ CREATE TABLE IF NOT EXISTS `aihr_practice_assignment` (
   `create_time` datetime DEFAULT NULL COMMENT '创建时间',
   `update_time` datetime DEFAULT NULL COMMENT '更新时间',
   PRIMARY KEY (`id`),
+  UNIQUE KEY `uk_aihr_assignment_request` (`tenant_id`, `request_key`, `ext_party_id`),
   KEY `idx_aihr_assignment_party` (`tenant_id`, `ext_party_id`, `status`, `create_time`),
   KEY `idx_aihr_assignment_source` (`tenant_id`, `source`, `status`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci COMMENT='AI HR 对练派发任务';