style(heures) : bouton export en MalioButton secondary (cohérent avec la liste employés)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/pages/hours.vue

@@ -2,15 +2,14 @@
     <div class="h-full overflow-hidden flex flex-col">
         <div class="flex flex-wrap items-center justify-between gap-4">
             <h1 class="text-2xl font-bold text-primary-500 lg:text-4xl">Heures</h1>
-            <button
+            <MalioButton
                 v-if="isAdmin"
-                type="button"
+                label="Export"
-                class="flex items-center gap-2 rounded-md bg-primary-500 px-4 py-2 text-md font-semibold text-white hover:bg-secondary-500"
+                variant="secondary"
+                icon-name="mdi:download"
+                icon-position="left"
                 @click="isExportDrawerOpen = true"
-            >
+            />
-                <Icon name="mdi:file-export-outline" />
-                Exporter
-            </button>
         </div>
 
         <HoursDayExportDrawer