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/PieceItem.vue

@@ -52,7 +52,7 @@
     </div>
 
     <div v-show="!isCollapsed" class="space-y-4">
-      <div class="p-4 bg-base-100 border border-gray-200 rounded-lg">
+      <div class="p-4 bg-base-100 border border-base-200 rounded-lg">
         <div class="space-y-2 text-sm">
       <div>
         <span class="font-medium">Référence:</span>
@@ -82,7 +82,7 @@
               </span>
               <span
                 v-if="formatConstructeurContact(constructeur)"
-                class="text-xs text-gray-500"
+                class="text-xs text-base-content/50"
               >
                 {{ formatConstructeurContact(constructeur) }}
               </span>
@@ -186,9 +186,9 @@
       @field-blur="handleCustomFieldBlur"
     />
 
-    <div class="mt-4 pt-4 border-t border-gray-200 space-y-3">
+    <div class="mt-4 pt-4 border-t border-base-200 space-y-3">
       <div class="flex items-center justify-between">
-        <h5 class="text-sm font-medium text-gray-700">Documents</h5>
+        <h5 class="text-sm font-medium text-base-content/80">Documents</h5>
         <span
           v-if="isEditMode && selectedFiles.length"
           class="badge badge-outline"
@@ -200,7 +200,7 @@
         </span>
       </div>
 
-      <p v-if="loadingDocuments" class="text-xs text-gray-500">
+      <p v-if="loadingDocuments" class="text-xs text-base-content/50">
         Chargement des documents...
       </p>