feat: 支持知识库 CSV 大文件导入

- 增加 CSV 流式解析、表格语义分块和分页预览

- 增加快照两阶段清理、失败重试和格式校验

- 补充批量入口、管理端交互和回归测试

easyflow-starter/easyflow-starter-all/src/main/resources/db/migration/mysql/V51__mysql_document_import_snapshot_cleanup.sql

@@ -0,0 +1,30 @@
+CREATE TABLE `tb_document_import_snapshot_cleanup`
+(
+    `id`              bigint UNSIGNED NOT NULL COMMENT '主键',
+    `knowledge_id`    bigint UNSIGNED NULL DEFAULT NULL COMMENT '知识库ID',
+    `document_id`     bigint UNSIGNED NULL DEFAULT NULL COMMENT '文档ID',
+    `snapshot_type`   varchar(32) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NOT NULL COMMENT '快照类型',
+    `manifest_path`   varchar(2048) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NOT NULL COMMENT '快照清单路径',
+    `path_hash`       char(64) CHARACTER SET ascii COLLATE ascii_bin NOT NULL COMMENT '快照清单路径SHA-256',
+    `phase`           varchar(32) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NOT NULL COMMENT '清理阶段',
+    `attempt_count`   int NOT NULL DEFAULT 0 COMMENT '已尝试次数',
+    `next_retry_at`   datetime NOT NULL COMMENT '下次重试时间',
+    `execution_token` varchar(64) CHARACTER SET ascii COLLATE ascii_bin NULL DEFAULT NULL COMMENT '执行令牌',
+    `lease_until`     datetime NULL DEFAULT NULL COMMENT '租约截止时间',
+    `last_error`      varchar(1024) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NULL DEFAULT NULL COMMENT '最近错误',
+    `created`         datetime NULL DEFAULT NULL COMMENT '创建时间',
+    `created_by`      bigint UNSIGNED NULL DEFAULT NULL COMMENT '创建人',
+    `modified`        datetime NULL DEFAULT NULL COMMENT '修改时间',
+    `modified_by`     bigint UNSIGNED NULL DEFAULT NULL COMMENT '修改人',
+    PRIMARY KEY (`id`) USING BTREE,
+    UNIQUE INDEX `uk_document_import_snapshot_cleanup_path`
+        (`snapshot_type`, `path_hash`) USING BTREE,
+    INDEX `idx_document_import_snapshot_cleanup_due`
+        (`next_retry_at`, `lease_until`, `id`) USING BTREE,
+    INDEX `idx_document_import_snapshot_cleanup_document`
+        (`document_id`, `snapshot_type`) USING BTREE
+) ENGINE = InnoDB
+  CHARACTER SET = utf8mb4
+  COLLATE = utf8mb4_0900_ai_ci
+  COMMENT = '文档导入中间快照清理记录'
+  ROW_FORMAT = DYNAMIC;