feat: BackupService real pg_dump, OrganisationService region stats, SystemConfigService overrides

- BackupService: DB-persisted metadata (BackupRecord/BackupConfig entities + V16 Flyway migration),
  real pg_dump execution via ProcessBuilder, soft-delete on deleteBackup, pg_restore manual guidance
- OrganisationService: repartitionRegion now queries Adresse entities (was Map.of() stub)
- SystemConfigService: in-memory config overrides via AtomicReference (no DB dependency)
- SystemMetricsService: null-guard on MemoryMXBean in getSystemStatus() (fixes test NPE)
- Souscription workflow: SouscriptionService, SouscriptionResource, FormuleAbonnementRepository,
  V11 Flyway migration, admin REST clients
- Flyway V8-V15: notes membres, types référence, type orga constraint, seed roles,
  première connexion, Wave checkout URL, Wave telephone column length fix
- .gitignore: added uploads/ and .claude/

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

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

@@ -0,0 +1,52 @@
+package dev.lions.unionflow.server.entity;
+
+import jakarta.persistence.*;
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Data;
+import lombok.EqualsAndHashCode;
+import lombok.NoArgsConstructor;
+
+@Entity
+@Table(name = "backup_config")
+@Data
+@Builder
+@NoArgsConstructor
+@AllArgsConstructor
+@EqualsAndHashCode(callSuper = true)
+public class BackupConfig extends BaseEntity {
+
+    @Column(nullable = false)
+    @Builder.Default
+    private Boolean autoBackupEnabled = true;
+
+    /** HOURLY, DAILY, WEEKLY */
+    @Column(nullable = false, length = 20)
+    @Builder.Default
+    private String frequency = "DAILY";
+
+    @Column(nullable = false)
+    @Builder.Default
+    private Integer retentionDays = 30;
+
+    /** HH:mm format, e.g. "02:00" */
+    @Column(nullable = false, length = 10)
+    @Builder.Default
+    private String backupTime = "02:00";
+
+    @Column(nullable = false)
+    @Builder.Default
+    private Boolean includeDatabase = true;
+
+    @Column(nullable = false)
+    @Builder.Default
+    private Boolean includeFiles = false;
+
+    @Column(nullable = false)
+    @Builder.Default
+    private Boolean includeConfiguration = true;
+
+    /** Absolute path where backup files are stored */
+    @Column(length = 500)
+    private String backupDirectory;
+}