fix(entity): @Column name explicite sur BackupConfig/BackupRecord

Sans @Column(name=...), Hibernate génère des noms camelCase (includedatabase)
alors que V16 a créé les colonnes en snake_case (include_database).
Alignement explicite avec les conventions des autres entités.

src/main/java/dev/lions/unionflow/server/entity/BackupConfig.java

@@ -16,37 +16,37 @@ import lombok.NoArgsConstructor;
 @EqualsAndHashCode(callSuper = true)
 public class BackupConfig extends BaseEntity {
 
-    @Column(nullable = false)
+    @Column(name = "auto_backup_enabled", nullable = false)
     @Builder.Default
     private Boolean autoBackupEnabled = true;
 
     /** HOURLY, DAILY, WEEKLY */
-    @Column(nullable = false, length = 20)
+    @Column(name = "frequency", nullable = false, length = 20)
     @Builder.Default
     private String frequency = "DAILY";
 
-    @Column(nullable = false)
+    @Column(name = "retention_days", nullable = false)
     @Builder.Default
     private Integer retentionDays = 30;
 
     /** HH:mm format, e.g. "02:00" */
-    @Column(nullable = false, length = 10)
+    @Column(name = "backup_time", nullable = false, length = 10)
     @Builder.Default
     private String backupTime = "02:00";
 
-    @Column(nullable = false)
+    @Column(name = "include_database", nullable = false)
     @Builder.Default
     private Boolean includeDatabase = true;
 
-    @Column(nullable = false)
+    @Column(name = "include_files", nullable = false)
     @Builder.Default
     private Boolean includeFiles = false;
 
-    @Column(nullable = false)
+    @Column(name = "include_configuration", nullable = false)
     @Builder.Default
     private Boolean includeConfiguration = true;
 
     /** Absolute path where backup files are stored */
-    @Column(length = 500)
+    @Column(name = "backup_directory", length = 500)
     private String backupDirectory;
 }