feat(app): 初始化 OmniScheduler WPF 调度器

基于 PRD 搭建 .NET 8 WPF 桌面应用，包含主控制台、任务编辑、全局设置、系统托盘和应用图标集成。

实现本地任务模型、触发器规则、JSON 状态持久化、OmniNotify HTTP 推送、执行日志记录、动态变量替换以及基础 Cron 预览能力。

补充 .gitignore，排除构建产物和本地 IDE 文件。

BREAKING CHANGE: 首次提交，建立项目初始结构

OmniScheduler/SettingsWindow.xaml.cs

@@ -0,0 +1,56 @@
+using System.Windows;
+
+namespace OmniScheduler;
+
+public partial class SettingsWindow : Window
+{
+    private readonly AppSettings _settings;
+
+    private SettingsWindow(Window owner, AppSettings settings)
+    {
+        InitializeComponent();
+        Owner = owner;
+        _settings = settings;
+        StartWithWindowsBox.IsChecked = settings.StartWithWindows;
+        UrlBox.Text = settings.OmniNotifyUrl;
+        RetentionDaysBox.Text = settings.LogRetentionDays.ToString();
+        MaxRecordsBox.Text = settings.MaxLogRecords.ToString();
+    }
+
+    public static bool Edit(Window owner, AppSettings settings)
+    {
+        var dialog = new SettingsWindow(owner, settings);
+        return dialog.ShowDialog() == true;
+    }
+
+    private void Save_Click(object sender, RoutedEventArgs e)
+    {
+        ValidationText.Text = "";
+        if (!Uri.TryCreate(UrlBox.Text.Trim(), UriKind.Absolute, out _))
+        {
+            ValidationText.Text = "API 地址格式不正确";
+            return;
+        }
+
+        if (!int.TryParse(RetentionDaysBox.Text, out var days) || days < 1)
+        {
+            ValidationText.Text = "日志保留天数至少为 1";
+            return;
+        }
+
+        if (!int.TryParse(MaxRecordsBox.Text, out var max) || max < 100)
+        {
+            ValidationText.Text = "最大日志条数至少为 100";
+            return;
+        }
+
+        _settings.StartWithWindows = StartWithWindowsBox.IsChecked == true;
+        _settings.OmniNotifyUrl = UrlBox.Text.Trim();
+        _settings.LogRetentionDays = days;
+        _settings.MaxLogRecords = max;
+        DialogResult = true;
+    }
+
+    private void Cancel_Click(object sender, RoutedEventArgs e)
+        => DialogResult = false;
+}