Refactor : renommage ClientBrief en Brief (plus générique)

- Brief.vue masque les boutons d'ajout pour extended-brief
- Éditable uniquement en back-office pour cette étape
- ClientBrief → Brief dans ProjectStep.vue

Ref #3

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/components/project/ProjectStep.vue

@@ -23,7 +23,7 @@ import 'dayjs/locale/fr';
 import { usePageStore } from '../../stores/page';
 import { computed, onMounted, useTemplateRef } from 'vue';
 import { useProjectStore } from '../../stores/project';
-import ClientBrief from './cards/ClientBrief.vue';
+import Brief from './cards/Brief.vue';
 import MultipleDocuments from './cards/MultipleDocuments.vue';
 import SimpleDocument from './cards/SimpleDocument.vue';
 import VirtualSample from './cards/VirtualSample.vue';
@@ -35,9 +35,9 @@ const { step } = defineProps({
 });
 
 const cardsMap = {
-  clientBrief: ClientBrief,
+  clientBrief: Brief,
   proposal: MultipleDocuments,
-  extendedBrief: ClientBrief,
+  extendedBrief: Brief,
   industrialIdeation: SimpleDocument,
   virtualSample: VirtualSample,
   physicalSample: PhysicalSample,

src/components/project/cards/Brief.vue

@@ -8,13 +8,13 @@
   <Document v-if="pdf" :step="step" :pdf="pdf" />
 
   <button
-    v-if="images.length === 0"
+    v-if="images.length === 0 && step.id === 'clientBrief'"
     class="btn | w-full"
     @click="goToImagesBrief()"
   >
     Ajouter un brief via la plateforme
   </button>
-  <div class="btn | w-full" v-if="!pdf">
+  <div class="btn | w-full" v-if="!pdf && step.id === 'clientBrief'">
     <label for="upload-pdf">
       Ajouter un brief PDF
       <input