centered file preview, made text copyable

lib/view/pages/talk/components/chatBubble.dart

@@ -206,7 +206,7 @@ class _ChatBubbleState extends State<ChatBubble> with SingleTickerProviderStateM
             ),
           ),
           Visibility(
-            visible: !message.containsFile,
+            visible: widget.bubbleData.message != '{file}',
             child: ListTile(
               leading: const Icon(Icons.copy),
               title: const Text('Nachricht kopieren'),

lib/view/pages/talk/components/chatMessage.dart

@@ -38,6 +38,10 @@ class ChatMessage {
         padding: const EdgeInsets.only(top: 5),
         child: Column(
           crossAxisAlignment: CrossAxisAlignment.start,
+          children: [
+            Row(
+              mainAxisSize: MainAxisSize.max,
+              mainAxisAlignment: MainAxisAlignment.center,
               children: [
                 CachedNetworkImage(
                   errorWidget: (context, url, error) => Row(
@@ -56,6 +60,8 @@ class ChatMessage {
                   fadeOutDuration: Duration.zero,
                   errorListener: (value) {},
                   imageUrl: 'https://${AccountData().buildHttpAuthString()}@${EndpointData().nextcloud().full()}/index.php/core/preview?fileId=${file!.id}&x=100&y=-1&a=1',
+                )
+              ],
             ),
             SizedBox(height: 5),
             contentWidget