fix: missing alt attribute & avoid stretching image

src/views/AttachmentPreview.vue

@@ -5,10 +5,12 @@
       :src="src"
       type="application/pdf"
     >
-    <img
-      v-else
-      :src="src"
-    >
+    <div v-else>
+      <img
+        :src="src"
+        :alt="`Aperçu ${is_pdf ? 'd\'un document pdf' : 'd\'une image'}`"
+      >
+    </div>
   </div>
 </template>
 
@@ -48,5 +50,9 @@ export default {
     height: 100%;
     width: 100%;
   }
+  > div {
+    display: flex;
+    justify-content: center;
+  }
 }
 </style>
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