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/DocumentUpload.vue

@@ -13,7 +13,7 @@
         <h3 class="font-semibold">
           {{ title }}
         </h3>
-        <p class="text-sm text-gray-500">
+        <p class="text-sm text-base-content/50">
           {{ subtitle }}
         </p>
       </div>
@@ -22,7 +22,7 @@
         <button type="button" class="btn btn-primary btn-sm" @click="triggerFileDialog">
           Sélectionner des fichiers
         </button>
-        <span class="text-xs text-gray-500">ou glisser-déposer ici</span>
+        <span class="text-xs text-base-content/50">ou glisser-déposer ici</span>
       </div>
 
       <input
@@ -54,7 +54,7 @@
             </div>
             <div class="flex flex-col">
               <span class="font-medium">{{ file.name }}</span>
-              <span class="text-xs text-gray-500">{{ formatSize(file.size) }} • {{ file.type || 'Type inconnu' }}</span>
+              <span class="text-xs text-base-content/50">{{ formatSize(file.size) }} • {{ file.type || 'Type inconnu' }}</span>
             </div>
           </div>
           <button type="button" class="btn btn-ghost btn-xs" @click="removeFile(file)">