feat(ui) : add site colors, dark mode toggle and card styling improvements

- Site color field with color picker in create/edit modals
- Dark mode theme (mytheme-dark) with toggle in navbar
- Stronger site color visibility on cards (gradient, top border, badges)
- Bigger action buttons (btn-sm) on machine cards
- White card backgrounds with proper dark mode support

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

app/components/machine/MachineProductsCard.vue

@@ -24,24 +24,26 @@
         <div
           v-for="product in products"
           :key="product.id || product.name"
-          class="rounded border border-base-200 bg-base-200/60 p-3 text-sm space-y-2 relative"
+          class="rounded border border-base-200 bg-base-200/60 p-3 text-sm space-y-2"
         >
-          <button
-            v-if="isEditMode"
-            type="button"
-            class="btn btn-error btn-xs absolute top-2 right-2"
-            title="Supprimer ce produit"
-            @click="$emit('remove-product', (product.linkId || product.id) as string)"
-          >
-            Supprimer
-          </button>
           <div class="flex items-center justify-between flex-wrap gap-2">
             <p class="font-semibold text-base-content">
               {{ product.name }}
             </p>
-            <span v-if="product.groupLabel" class="badge badge-ghost badge-sm">
-              {{ product.groupLabel }}
-            </span>
+            <div class="flex items-center gap-2">
+              <span v-if="product.groupLabel" class="badge badge-ghost badge-sm">
+                {{ product.groupLabel }}
+              </span>
+              <button
+                v-if="isEditMode"
+                type="button"
+                class="btn btn-ghost btn-xs text-error"
+                title="Supprimer ce produit"
+                @click="$emit('remove-product', (product.linkId || product.id) as string)"
+              >
+                Supprimer
+              </button>
+            </div>
           </div>
           <p v-if="product.reference" class="text-xs text-base-content/70">
             <span class="font-medium">Référence :</span>