feat: add 'Always show current HEAD on the left' option for commit graph

添加“HEAD 路径永远显示在最左边”选项：
1. 在 Preferences 中添加开关及对应多语言翻译。
2. 优化 CommitGraph 解析算法：
    - 预扫描 HEAD 及其后续提交路径（Forward Lineage）。
    - 引入“列预留”机制：在未识别到 HEAD 路径前，强制预留最左侧列。
    - 引入“动态重排”机制：在处理每一行前，确保识别到的 HEAD 路径位于活动路径列表的最前端（索引 0）。
    - 修复了并行分支因并入 HEAD 祖先而被误判为 HEAD 主干的问题。
3. 确保视觉上 HEAD 路径始终占据最左侧位置，增强复杂分支环境下的可读性。

FAILED test cases: NONE

Author: heartacker

src/Models/CommitGraph.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 
 using Avalonia;
@@ -62,7 +62,7 @@ public class Dot
         public List<Link> Links { get; } = [];
         public List<Dot> Dots { get; } = [];
 
-        public static CommitGraph Parse(List<Commit> commits, bool firstParentOnlyEnabled)
+        public static CommitGraph Parse(List<Commit> commits, bool firstParentOnlyEnabled, bool alwaysShowCurrentHeadOnLeft)
         {
             const double unitWidth = 12;
             const double halfWidth = 6;
@@ -75,6 +75,24 @@ public static CommitGraph Parse(List<Commit> commits, bool firstParentOnlyEnable
             var offsetY = -halfHeight;
             var colorPicker = new ColorPicker();
 
+            var headPathSHAs = new HashSet<string>();
+            if (alwaysShowCurrentHeadOnLeft)
+            {
+                var head = commits.Find(x => x.IsCurrentHead);
+                if (head != null)
+                {
+                    headPathSHAs.Add(head.SHA);
+
+                    // Forward (newer commits leading to HEAD)
+                    for (int i = commits.IndexOf(head) - 1; i >= 0; i--)
+                    {
+                        if (commits[i].Parents.Count > 0 && headPathSHAs.Contains(commits[i].Parents[0]))
+                            headPathSHAs.Add(commits[i].SHA);
+                    }
+                }
+            }
+
+            PathHelper headPath = null;
             foreach (var commit in commits)
             {
                 PathHelper major = null;
@@ -83,9 +101,26 @@ public static CommitGraph Parse(List<Commit> commits, bool firstParentOnlyEnable
                 // Update current y offset
                 offsetY += unitHeight;
 
-                // Find first curves that links to this commit and marks others that links to this commit ended.
+                // 1. Move HEAD path to the front of unsolved list (index 0)
+                if (alwaysShowCurrentHeadOnLeft && headPath != null && unsolved.Contains(headPath))
+                {
+                    unsolved.Remove(headPath);
+                    unsolved.Insert(0, headPath);
+                }
+
+                // 2. Reserve leftmost column (offsetX) for HEAD path if not yet found
                 var offsetX = 4 - halfWidth;
-                var maxOffsetOld = unsolved.Count > 0 ? unsolved[^1].LastX : offsetX + unitWidth;
+                if (alwaysShowCurrentHeadOnLeft && headPath == null)
+                    offsetX += unitWidth;
+
+                // 3. Keep track of max offsetX used in previous rows for margin calculation
+                var maxOffsetOld = 0.0;
+                foreach (var l in unsolved)
+                    maxOffsetOld = Math.Max(maxOffsetOld, l.LastX);
+                if (unsolved.Count == 0)
+                    maxOffsetOld = offsetX + unitWidth;
+
+                // 4. Process existing paths
                 foreach (var l in unsolved)
                 {
                     if (l.Next.Equals(commit.SHA, StringComparison.Ordinal))
@@ -129,14 +164,24 @@ public static CommitGraph Parse(List<Commit> commits, bool firstParentOnlyEnable
                 }
                 ended.Clear();
 
-                // If no path found, create new curve for branch head
-                // Otherwise, create new curve for new merged commit
+                // 5. Create new curve for branch tip or new merged commit
                 if (major == null)
                 {
-                    offsetX += unitWidth;
-
-                    if (commit.Parents.Count > 0)
+                    // If this is the start of the HEAD lineage, place it in the reserved column (index 0)
+                    if (alwaysShowCurrentHeadOnLeft && headPath == null && headPathSHAs.Contains(commit.SHA))
                     {
+                        if (commit.Parents.Count > 0)
+                        {
+                            var headX = 4 - halfWidth + unitWidth;
+                            major = new PathHelper(commit.Parents[0], isMerged, colorPicker.Next(), new Point(headX, offsetY));
+                            headPath = major;
+                            unsolved.Insert(0, major);
+                            temp.Paths.Add(major.Path);
+                        }
+                    }
+                    else if (commit.Parents.Count > 0)
+                    {
+                        offsetX += unitWidth;
                         major = new PathHelper(commit.Parents[0], isMerged, colorPicker.Next(), new Point(offsetX, offsetY));
                         unsolved.Add(major);
                         temp.Paths.Add(major.Path);

src/Resources/Locales/en_US.axaml

@@ -653,6 +653,8 @@
   <x:String x:Key="Text.Preferences.DiffMerge.Path.Placeholder" xml:space="preserve">Input path for diff/merge tool</x:String>
   <x:String x:Key="Text.Preferences.DiffMerge.Type" xml:space="preserve">Tool</x:String>
   <x:String x:Key="Text.Preferences.General" xml:space="preserve">GENERAL</x:String>
+  <x:String x:Key="Text.Preferences.General.AllowMarkdownNetworkImages" xml:space="preserve">Allow loading network images in Markdown preview</x:String>
+  <x:String x:Key="Text.Preferences.General.AlwaysShowCurrentHeadOnLeft" xml:space="preserve">Always show current HEAD on the left</x:String>
   <x:String x:Key="Text.Preferences.General.Check4UpdatesOnStartup" xml:space="preserve">Check for updates on startup</x:String>
   <x:String x:Key="Text.Preferences.General.DateFormat" xml:space="preserve">Date Format</x:String>
   <x:String x:Key="Text.Preferences.General.EnableCompactFolders" xml:space="preserve">Enable compact folders in changes tree</x:String>

src/Resources/Locales/zh_CN.axaml

@@ -657,7 +657,9 @@
   <x:String x:Key="Text.Preferences.DiffMerge.Path.Placeholder" xml:space="preserve">填写工具可执行文件所在位置</x:String>
   <x:String x:Key="Text.Preferences.DiffMerge.Type" xml:space="preserve">工具</x:String>
   <x:String x:Key="Text.Preferences.General" xml:space="preserve">通用配置</x:String>
-  <x:String x:Key="Text.Preferences.General.Check4UpdatesOnStartup" xml:space="preserve">启动时检测软件更新</x:String>
+  <x:String x:Key="Text.Preferences.General.AllowMarkdownNetworkImages" xml:space="preserve">允许在 Markdown 预览中加载网络图片</x:String>
+  <x:String x:Key="Text.Preferences.General.AlwaysShowCurrentHeadOnLeft" xml:space="preserve">HEAD 路径永远显示在最左边</x:String>
+  <x:String x:Key="Text.Preferences.General.Check4UpdatesOnStartup" xml:space="preserve">启动时检查更新</x:String>
   <x:String x:Key="Text.Preferences.General.DateFormat" xml:space="preserve">日期时间格式</x:String>
   <x:String x:Key="Text.Preferences.General.EnableCompactFolders" xml:space="preserve">在变更列表树中启用紧凑文件夹模式</x:String>
   <x:String x:Key="Text.Preferences.General.Locale" xml:space="preserve">显示语言</x:String>

src/ViewModels/Preferences.cs

@@ -217,6 +217,12 @@ public bool ShowTagsInGraph
             set => SetProperty(ref _showTagsInGraph, value);
         }
 
+        public bool AlwaysShowCurrentHeadOnLeftInGraph
+        {
+            get => _alwaysShowCurrentHeadOnLeftInGraph;
+            set => SetProperty(ref _alwaysShowCurrentHeadOnLeftInGraph, value);
+        }
+
         public bool UseTwoColumnsLayoutInHistories
         {
             get => _useTwoColumnsLayoutInHistories;
@@ -833,6 +839,7 @@ private bool RemoveInvalidRepositoriesRecursive(List<RepositoryNode> collection)
         private string _ignoreUpdateTag = string.Empty;
 
         private bool _showTagsInGraph = true;
+        private bool _alwaysShowCurrentHeadOnLeftInGraph = false;
         private bool _useTwoColumnsLayoutInHistories = false;
         private bool _displayTimeAsPeriodInHistories = false;
         private bool _useSideBySideDiff = false;

src/ViewModels/Repository.cs

@@ -1211,8 +1211,10 @@ public void RefreshCommits()
                     .Append('-').Append(Preferences.Instance.MaxHistoryCommits).Append(' ')
                     .Append(_uiStates.BuildHistoryParams());
 
-                var commits = await new Commands.QueryCommits(FullPath, builder.ToString()).GetResultAsync().ConfigureAwait(false);
-                var graph = Models.CommitGraph.Parse(commits, _uiStates.HistoryShowFlags.HasFlag(Models.HistoryShowFlags.FirstParentOnly));
+                var commits = await new Commands.QueryCommits(FullPath, builder.ToString(), true, patterns).GetResultAsync().ConfigureAwait(false);
+                var graph = Models.CommitGraph.Parse(commits,
+                    _uiStates.HistoryShowFlags.HasFlag(Models.HistoryShowFlags.FirstParentOnly),
+                    Preferences.Instance.AlwaysShowCurrentHeadOnLeftInGraph);
 
                 Dispatcher.UIThread.Invoke(() =>
                 {

src/Views/Preferences.axaml

@@ -48,6 +48,7 @@
             <TextBlock Classes="tab_header" Text="{DynamicResource Text.Preferences.General}"/>
           </TabItem.Header>
           <Grid Margin="8" RowDefinitions="32,32,32,32,32,32,32,32,32,32,32,32,Auto" ColumnDefinitions="Auto,*">
+          <Grid Margin="8" RowDefinitions="32,32,32,32,32,32,32,32,32,32,32,32,32,32,Auto" ColumnDefinitions="Auto,*">
             <TextBlock Grid.Row="0" Grid.Column="0"
                        Text="{DynamicResource Text.Preferences.General.Locale}"
                        HorizontalAlignment="Right"
@@ -167,16 +168,26 @@
                       IsChecked="{Binding ShowChildren, Mode=TwoWay}"/>
 
             <CheckBox Grid.Row="10" Grid.Column="1"
+                      Height="32"
+                      Content="{DynamicResource Text.Preferences.General.AlwaysShowCurrentHeadOnLeft}"
+                      IsChecked="{Binding AlwaysShowCurrentHeadOnLeftInGraph, Mode=TwoWay}"/>
+
+            <CheckBox Grid.Row="11" Grid.Column="1"
                       Height="32"
                       Content="{DynamicResource Text.Preferences.General.EnableCompactFolders}"
                       IsChecked="{Binding EnableCompactFoldersInChangesTree, Mode=TwoWay}"/>
 
-            <CheckBox Grid.Row="11" Grid.Column="1"
+            <CheckBox Grid.Row="12" Grid.Column="1"
                       Height="32"
                       Content="{DynamicResource Text.Preferences.General.UseGitHubStyleAvatar}"
                       IsChecked="{Binding UseGitHubStyleAvatar, Mode=TwoWay}"/>
 
-            <CheckBox Grid.Row="12" Grid.Column="1"
+            <CheckBox Grid.Row="13" Grid.Column="1"
+                      Height="32"
+                      Content="{DynamicResource Text.Preferences.General.AllowMarkdownNetworkImages}"
+                      IsChecked="{Binding AllowMarkdownNetworkImages, Mode=TwoWay}"/>
+
+            <CheckBox Grid.Row="14" Grid.Column="1"
                       Height="32"
                       Content="{DynamicResource Text.Preferences.General.Check4UpdatesOnStartup}"
                       IsVisible="{x:Static s:App.IsCheckForUpdateCommandVisible}"