✨ 异常处置跟进支持上传附件

跟进记录新增 attachments_json 列，存 [{name, url}] 形式的 JSON 数组。
跟进说明与附件至少填其一即可：只传附件时，follow_content 列为 NOT NULL，
故写入固定文案「已上传跟进附件」，列表按该文案展示。

建表脚本补 COLLATE：原先只写 CHARSET，落到 MySQL 8 服务器默认排序规则，
与库中实际的 utf8mb4_0900_ai_ci 不一致。

blade-service-api/blade-transport-api/src/main/java/org/springblade/transport/pojo/dto/ExceptionDisposalFollowRequest.java

@@ -46,4 +46,7 @@ public class ExceptionDisposalFollowRequest implements Serializable {
 	@Schema(description = "跟进说明")
 	private String followContent;
 
+	@Schema(description = "附件JSON，[{\"name\":\"...\",\"url\":\"...\"}]")
+	private String attachmentsJson;
+
 }

blade-service-api/blade-transport-api/src/main/java/org/springblade/transport/pojo/entity/ExceptionDisposalFollowRecord.java

@@ -51,6 +51,9 @@ public class ExceptionDisposalFollowRecord extends TenantEntity {
 	@Schema(description = "跟进说明")
 	private String followContent;
 
+	@Schema(description = "附件JSON")
+	private String attachmentsJson;
+
 	@Schema(description = "跟进人")
 	private Long followUser;