Add concept of maximum depth when rendering comment chains, set to 5 initially

lib/controls/timeline/flattened_tree_entry_control.dart

@@ -1,3 +1,5 @@
+import 'dart:math';
+
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:go_router/go_router.dart';
@@ -26,6 +28,9 @@ import 'interactions_bar_control.dart';
 import 'link_preview_control.dart';
 import 'status_header_control.dart';
 
+const maxDepth = 5.0;
+const otherPadding = 8.0;
+
 class FlattenedTreeEntryControl extends StatefulWidget {
   final FlattenedTreeItem originalItem;
   final bool openRemote;
@@ -76,8 +81,8 @@ class _StatusControlState extends State<FlattenedTreeEntryControl> {
 
     filteringInfo = filterService.checkTimelineEntry(entry);
 
-    const otherPadding = 8.0;
-    final leftPadding = otherPadding + (widget.originalItem.level * 15.0);
+    final leftPadding =
+        otherPadding + (min(maxDepth, widget.originalItem.level) * 15.0);
     final color = widget.originalItem.level.isOdd
         ? Theme.of(context).secondaryHeaderColor
         : Theme.of(context).dialogBackgroundColor;