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/cards/ClientBrief.vue

@@ -1,54 +0,0 @@
-<template>
-  <Images
-    v-if="images.length > 0"
-    :step="step"
-    :images="images"
-    :uri="'/' + step.uri"
-  />
-  <Document v-if="pdf" :step="step" :pdf="pdf" />
-
-  <button
-    v-if="images.length === 0"
-    class="btn | w-full"
-    @click="goToImagesBrief()"
-  >
-    Ajouter un brief via la plateforme
-  </button>
-  <div class="btn | w-full" v-if="!pdf">
-    <label for="upload-pdf">
-      Ajouter un brief PDF
-      <input
-        id="upload-pdf"
-        type="file"
-        @change="addPdf($event, step.uri)"
-        accept="application/pdf"
-        ref="pdfInput"
-        hidden
-      />
-    </label>
-  </div>
-</template>
-
-<script setup>
-import { computed } from "vue";
-import Images from "./Images.vue";
-import Document from "./Document.vue";
-import { useBriefStore } from "../../../stores/brief";
-import { useRouter } from "vue-router";
-
-const { step } = defineProps({ step: Object });
-const { addPdf } = useBriefStore();
-const router = useRouter();
-
-const images = computed(() => {
-  return step.files.filter((file) => file.type === "image");
-});
-
-const pdf = computed(() => {
-  return step.files.find((file) => file.type === "document");
-});
-
-function goToImagesBrief() {
-  router.push(location.pathname + "/" + step.slug);
-}
-</script>