Add tray About menu, sync-on-start, sync lock

- "Ueber" menu item in tray context menu opens About dialog
- New user setting "Beim Start automatisch synchronisieren"
  syncs all enabled profiles once at app startup
- Sync lock prevents concurrent sync runs (timer, manual,
  on-start cannot overlap - second request is skipped)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/StarfaceOutlookSync/Models/UserSettings.cs

@@ -7,6 +7,7 @@ namespace StarfaceOutlookSync.Models
     public class UserSettings
     {
         public bool StartMinimized { get; set; } = false;
+        public bool SyncOnStart { get; set; } = false;
 
         private static readonly string SettingsFile = Path.Combine(
             Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData),

src/StarfaceOutlookSync/UI/MainForm.cs

@@ -22,6 +22,7 @@ namespace StarfaceOutlookSync.UI
         private StatusStrip _statusBar;
         private ToolStripStatusLabel _statusLabel;
         private Timer _autoSyncTimer;
+        private volatile bool _syncRunning = false;
 
         public MainForm()
         {
@@ -38,6 +39,21 @@ namespace StarfaceOutlookSync.UI
                 ShowInTaskbar = false;
                 Visible = false;
             }
+
+            // Beim Start automatisch synchronisieren
+            if (settings.SyncOnStart)
+            {
+                _ = SyncAllProfiles();
+            }
+        }
+
+        private async Task SyncAllProfiles()
+        {
+            var profiles = _profileManager.GetProfiles().Where(p => p.Enabled).ToList();
+            foreach (var profile in profiles)
+            {
+                await RunSync(profile);
+            }
         }
 
         protected override void SetVisibleCore(bool value)
@@ -158,6 +174,7 @@ namespace StarfaceOutlookSync.UI
             if (profiles.Any(p => p.Enabled))
                 _trayMenu.Items.Add("-");
 
+            _trayMenu.Items.Add("Ueber", null, (s, e) => ShowAbout());
             _trayMenu.Items.Add("Beenden", null, (s, e) => ExitApplication());
         }
 
@@ -318,6 +335,13 @@ namespace StarfaceOutlookSync.UI
 
         private async Task RunSync(SyncProfile profile)
         {
+            if (_syncRunning)
+            {
+                SetStatus("Sync laeuft bereits, bitte warten...");
+                return;
+            }
+
+            _syncRunning = true;
             try
             {
                 SetStatus($"Synchronisiere '{profile.Name}'...");
@@ -340,6 +364,10 @@ namespace StarfaceOutlookSync.UI
                     ex.Message, ToolTipIcon.Error);
                 SetStatus($"Fehler: {ex.Message}");
             }
+            finally
+            {
+                _syncRunning = false;
+            }
         }
 
         private void SetStatus(string text)

src/StarfaceOutlookSync/UI/SettingsForm.cs

@@ -6,7 +6,7 @@ namespace StarfaceOutlookSync.UI
 {
     public class SettingsForm : Form
     {
-        private CheckBox _chkStartMinimized;
+        private CheckBox _chkStartMinimized, _chkSyncOnStart;
         private Button _btnSave, _btnCancel;
         private readonly UserSettings _settings;
 
@@ -19,7 +19,7 @@ namespace StarfaceOutlookSync.UI
         private void InitializeComponent()
         {
             Text = "Einstellungen";
-            Size = new Size(350, 180);
+            Size = new Size(350, 210);
             FormBorderStyle = FormBorderStyle.FixedDialog;
             MaximizeBox = false;
             MinimizeBox = false;
@@ -33,20 +33,27 @@ namespace StarfaceOutlookSync.UI
                 Checked = _settings.StartMinimized
             };
 
+            _chkSyncOnStart = new CheckBox
+            {
+                Text = "Beim Start automatisch synchronisieren",
+                Left = 20, Top = 52, AutoSize = true,
+                Checked = _settings.SyncOnStart
+            };
+
             _btnSave = new Button
             {
-                Text = "Speichern", Left = 80, Top = 100, Width = 85, Height = 28,
+                Text = "Speichern", Left = 80, Top = 130, Width = 85, Height = 28,
                 DialogResult = DialogResult.None
             };
             _btnSave.Click += (s, e) => Save();
 
             _btnCancel = new Button
             {
-                Text = "Abbrechen", Left = 174, Top = 100, Width = 85, Height = 28,
+                Text = "Abbrechen", Left = 174, Top = 130, Width = 85, Height = 28,
                 DialogResult = DialogResult.Cancel
             };
 
-            Controls.AddRange(new Control[] { _chkStartMinimized, _btnSave, _btnCancel });
+            Controls.AddRange(new Control[] { _chkStartMinimized, _chkSyncOnStart, _btnSave, _btnCancel });
             AcceptButton = _btnSave;
             CancelButton = _btnCancel;
         }
@@ -54,6 +61,7 @@ namespace StarfaceOutlookSync.UI
         private void Save()
         {
             _settings.StartMinimized = _chkStartMinimized.Checked;
+            _settings.SyncOnStart = _chkSyncOnStart.Checked;
             _settings.Save();
             DialogResult = DialogResult.OK;
             Close();