v2: empty sections fallback in synthesis detail view

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

frontend/src/i18n/fr.ts

@@ -97,6 +97,7 @@ const fr = {
   'synthesis.loadError': 'Erreur lors du chargement de la synthese.',
   'synthesis.deleteError': 'Erreur lors de la suppression.',
   'synthesis.backToHome': 'Retour a l\'accueil',
+  'synthesis.noSections': 'Aucune section trouvee dans cette synthese.',
 
   // Synthesis - Email
   'synthesis.email.title': 'Envoyer par email',

frontend/src/pages/SynthesisDetail.tsx

@@ -356,11 +356,18 @@ const SynthesisDetail: Component = () => {
 
             {/* Sections */}
             <div class="space-y-12">
-              <For each={synth().sections}>
-                {(section) => (
-                  <Section title={section.title} items={section.items} />
-                )}
-              </For>
+              <Show
+                when={synth().sections && synth().sections.length > 0}
+                fallback={
+                  <p class="text-center text-gray-500 italic py-12">
+                    {t('synthesis.noSections')}
+                  </p>
+                }
+              >
+                <For each={synth().sections}>
+                  {(section) => <Section title={section.title} items={section.items} />}
+                </For>
+              </Show>
             </div>
           </div>
         )}