refactor(ui) : improve styling, layout and responsive across all components

Rework CSS theme (app.css), navbar layout, dashboard page, machine detail,
catalog pages, and various form/display components for better consistency
and mobile responsiveness.

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

app/components/common/CustomFieldDisplay.vue

@@ -1,9 +1,9 @@
 <template>
   <div
     v-if="fields.length"
-    class="mt-4 pt-4 border-t border-gray-200"
+    class="mt-4 pt-4 border-t border-base-200"
   >
-    <h5 class="text-sm font-medium text-gray-700 mb-3">
+    <h5 class="text-sm font-medium text-base-content/80 mb-3">
       Champs personnalisés
     </h5>
     <div :class="layoutClass">