Refactor SAML configuration deployment and enhance Authentik integration

- Removed SAML configuration deployment calls from PostInstanceInitService.
- Updated DeploySamlConfigurationAsync to improve template fetching logic from Git and local directories.
- Added Authentik flow and keypair models for better representation in the UI.
- Enhanced SettingsViewModel to include Authentik settings with save and test functionality.
- Updated UI to support Authentik configuration, including dropdowns for flows and keypairs.
- Changed default CMS server name template to "app.ots-signs.com" across various files.
- Improved password handling in SshDockerCliService for secure shell command execution.
- Added new template file for settings-custom.php in the project structure.

OTSSignsOrchestrator.Core/Models/DTOs/AuthentikFlowItem.cs

@@ -0,0 +1,17 @@
+namespace OTSSignsOrchestrator.Core.Models.DTOs;
+
+/// <summary>
+/// Represents an Authentik flow for display in the Settings UI.
+/// </summary>
+public class AuthentikFlowItem
+{
+    public string Pk { get; set; } = string.Empty;
+    public string Slug { get; set; } = string.Empty;
+    public string Name { get; set; } = string.Empty;
+    public string Designation { get; set; } = string.Empty;
+
+    /// <summary>Display text for ComboBox: "slug — Name".</summary>
+    public string DisplayText => $"{Slug}  —  {Name}";
+
+    public override string ToString() => DisplayText;
+}

OTSSignsOrchestrator.Core/Models/DTOs/AuthentikKeypairItem.cs

@@ -0,0 +1,15 @@
+namespace OTSSignsOrchestrator.Core.Models.DTOs;
+
+/// <summary>
+/// Represents an Authentik certificate keypair for display in the Settings UI.
+/// </summary>
+public class AuthentikKeypairItem
+{
+    public string Pk { get; set; } = string.Empty;
+    public string Name { get; set; } = string.Empty;
+
+    /// <summary>Display text for ComboBox.</summary>
+    public string DisplayText => $"{Name}  ({Pk[..Math.Min(8, Pk.Length)]})";
+
+    public override string ToString() => DisplayText;
+}