fix: SystemAlert @PrePersist override + types_reference complete schema in V1

- SystemAlert.onCreate() now calls super.onCreate() to set dateCreation (was null → NOT NULL violation every minute)
- V1: types_reference updated with full schema (domaine, est_defaut, est_systeme, ordre_affichage, modules_requis, organisation_id)
- V9: idempotent guard for categorie nullable ALTER (already nullable in updated V1)

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

@@ -108,6 +108,7 @@ public class SystemAlert extends BaseEntity {
      */
     @PrePersist
     protected void onCreate() {
+        super.onCreate();
         if (timestamp == null) {
             timestamp = LocalDateTime.now();
         }

src/main/resources/db/migration/V1__UnionFlow_Complete_Schema.sql

@@ -1055,16 +1055,23 @@ CREATE TABLE IF NOT EXISTS ayants_droit (
 -- Table types_reference
 CREATE TABLE IF NOT EXISTS types_reference (
     id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    domaine VARCHAR(50) NOT NULL,
     code VARCHAR(50) NOT NULL,
-    categorie VARCHAR(50) NOT NULL,
+    categorie VARCHAR(50),
     libelle VARCHAR(200) NOT NULL,
     description TEXT,
-    ordre INTEGER DEFAULT 0,
+    ordre_affichage INTEGER NOT NULL DEFAULT 0,
+    est_defaut BOOLEAN NOT NULL DEFAULT FALSE,
+    est_systeme BOOLEAN NOT NULL DEFAULT FALSE,
+    modules_requis VARCHAR(500),
+    organisation_id UUID,
     date_creation TIMESTAMP NOT NULL DEFAULT NOW(),
     date_modification TIMESTAMP,
     version BIGINT DEFAULT 0,
     actif BOOLEAN NOT NULL DEFAULT TRUE,
-    CONSTRAINT uk_type_ref UNIQUE (categorie, code)
+    cree_par VARCHAR(255),
+    modifie_par VARCHAR(255),
+    CONSTRAINT uk_typeref_domaine_code_org UNIQUE (domaine, code, organisation_id)
 );
 
 -- Table modules_organisation_actifs

src/main/resources/db/migration/V9__Fix_TypesReference_Categorie_Nullable.sql

@@ -4,6 +4,11 @@
 -- no longer includes this column, causing INSERT to fail with NOT NULL violation.
 -- Also drop the old unique constraint on (categorie, code) which references the old design.
 
-ALTER TABLE types_reference ALTER COLUMN categorie DROP NOT NULL;
+-- categorie is already nullable in V1 (updated schema), these are idempotent safety guards
+DO $$ BEGIN
+    IF EXISTS (SELECT 1 FROM information_schema.columns WHERE table_name='types_reference' AND column_name='categorie' AND is_nullable='NO') THEN
+        ALTER TABLE types_reference ALTER COLUMN categorie DROP NOT NULL;
+    END IF;
+END $$;
 
 ALTER TABLE types_reference DROP CONSTRAINT IF EXISTS uk_type_ref;