use AppProgressIndicator for plain loading spinners

lib/widget/debug/cache_view.dart

@@ -7,6 +7,7 @@ import 'package:localstore/localstore.dart';
 
 import '../../../widget/placeholder_view.dart';
 import '../../api/request_cache.dart';
+import '../app_progress_indicator.dart';
 import 'json_viewer.dart';
 
 class CacheView extends StatefulWidget {
@@ -71,7 +72,7 @@ class _CacheViewState extends State<CacheView> {
             },
           );
         } else if (snapshot.connectionState != ConnectionState.done) {
-          return const Center(child: CircularProgressIndicator());
+          return const Center(child: AppProgressIndicator.large());
         } else {
           return const Center(
             child: PlaceholderView(

lib/widget/prosemirror/pm_json_view.dart

@@ -2,6 +2,7 @@ import 'package:cached_network_image/cached_network_image.dart';
 import 'package:collection/collection.dart';
 import 'package:flutter/material.dart';
 
+import '../app_progress_indicator.dart';
 import 'pm_document_view.dart';
 import 'pm_node.dart';
 
@@ -116,7 +117,7 @@ class _PmJsonViewState extends State<PmJsonView> {
     if (shown == null) {
       return const SizedBox(
         height: 160,
-        child: Center(child: CircularProgressIndicator()),
+        child: Center(child: AppProgressIndicator.large()),
       );
     }
     return PmDocumentView(doc: shown, onLinkTap: widget.onLinkTap);