Write Outlook security keys to HKLM for domain environments

On domain PCs, HKCU policies are controlled by GPO and the
Trust Center settings are greyed out. Now also writes to HKLM
(requires admin rights) which overrides GPO settings.

Shows orange hint in settings when GPO lock is detected:
"Auf Domaenen-PCs: App einmalig als Admin starten!"

The app tries all 8 combinations: HKCU/HKLM x Policies/direct
x 16.0/15.0. Silently skips paths where permissions are denied.

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

src/StarfaceOutlookSync/UI/SettingsForm.cs

@@ -47,11 +47,15 @@ namespace StarfaceOutlookSync.UI
                 Checked = _settings.AutoAcceptOutlookPrompt
             };
 
+            var hintText = "Hinweis: Outlook muss nach Aenderung neu gestartet werden.";
+            if (UserSettings.IsOutlookSecurityLockedByPolicy())
+                hintText += "\nAuf Domaenen-PCs: App einmalig als Admin starten!";
+
             var lblHint = new Label
             {
-                Text = "Hinweis: Outlook muss nach Aenderung dieser Option\nneu gestartet werden.",
-                Left = 38, Top = 102, Width = 300, Height = 32,
-                ForeColor = Color.Gray,
+                Text = hintText,
+                Left = 38, Top = 102, Width = 310, Height = 36,
+                ForeColor = UserSettings.IsOutlookSecurityLockedByPolicy() ? Color.OrangeRed : Color.Gray,
                 Font = new Font("Segoe UI", 8)
             };