feat(#159): suppressions métier dossiers/parents/enfants/AM/staff.

SuppressionService + DELETE /dossiers/:numero, cascades DELETE /users et
DELETE /enfants?deleteDossier, flag sans_enfant, specs front #160.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/src/app.module.ts

@@ -18,6 +18,7 @@ import { AppConfigModule } from './modules/config/config.module';
 import { DocumentsLegauxModule } from './modules/documents-legaux';
 import { RelaisModule } from './routes/relais/relais.module';
 import { DossiersModule } from './routes/dossiers/dossiers.module';
+import { SuppressionsModule } from './routes/suppressions/suppressions.module';
 
 @Module({
   imports: [
@@ -57,6 +58,7 @@ import { DossiersModule } from './routes/dossiers/dossiers.module';
     DocumentsLegauxModule,
     RelaisModule,
     DossiersModule,
+    SuppressionsModule,
   ],
   controllers: [AppController],
   providers: [