chore: Make stickers smaller than normal image messages

lib/pages/chat/events/message_content.dart

@@ -118,7 +118,8 @@ class MessageContent extends StatelessWidget {
           case MessageTypes.Image:
           case MessageTypes.Sticker:
             if (event.redacted) continue textmessage;
-            const maxSize = 256.0;
+            final maxSize =
+                event.messageType == MessageTypes.Sticker ? 128.0 : 256.0;
             final w = event.content
                 .tryGetMap<String, Object?>('info')
                 ?.tryGet<int>('w');

lib/pages/chat/sticker_picker_dialog.dart

@@ -67,7 +67,9 @@ class StickerPickerDialogState extends State<StickerPickerDialog> {
           GridView.builder(
             itemCount: imageKeys.length,
             gridDelegate: const SliverGridDelegateWithMaxCrossAxisExtent(
-              maxCrossAxisExtent: 128,
+              maxCrossAxisExtent: 84,
+              mainAxisSpacing: 8.0,
+              crossAxisSpacing: 8.0,
             ),
             shrinkWrap: true,
             physics: const NeverScrollableScrollPhysics(),