feat: Add main application views and structure

- Implemented CreateInstanceView for creating new instances.
- Added HostsView for managing SSH hosts with CRUD operations.
- Created InstancesView for displaying and managing instances.
- Developed LogsView for viewing operation logs.
- Introduced SecretsView for managing secrets associated with hosts.
- Established SettingsView for configuring application settings.
- Created MainWindow as the main application window with navigation.
- Added app manifest and configuration files for logging and settings.

OTSSignsOrchestrator.Core/Models/Entities/CmsInstance.cs

@@ -0,0 +1,117 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace OTSSignsOrchestrator.Core.Models.Entities;
+
+public enum InstanceStatus
+{
+    Deploying,
+    Active,
+    Error,
+    Deleted
+}
+
+public enum XiboApiTestStatus
+{
+    Unknown,
+    Success,
+    Failed
+}
+
+public class CmsInstance
+{
+    [Key]
+    public Guid Id { get; set; } = Guid.NewGuid();
+
+    [Required, MaxLength(100)]
+    public string CustomerName { get; set; } = string.Empty;
+
+    /// <summary>Exactly 3 lowercase letters used to derive all resource names.</summary>
+    [MaxLength(3)]
+    public string CustomerAbbrev { get; set; } = string.Empty;
+
+    [Required, MaxLength(100)]
+    public string StackName { get; set; } = string.Empty;
+
+    [Required, MaxLength(200)]
+    public string CmsServerName { get; set; } = string.Empty;
+
+    [Required, Range(1024, 65535)]
+    public int HostHttpPort { get; set; }
+
+    [Required, MaxLength(500)]
+    public string ThemeHostPath { get; set; } = string.Empty;
+
+    [Required, MaxLength(500)]
+    public string LibraryHostPath { get; set; } = string.Empty;
+
+    [Required, MaxLength(200)]
+    public string SmtpServer { get; set; } = string.Empty;
+
+    [Required, MaxLength(200)]
+    public string SmtpUsername { get; set; } = string.Empty;
+
+    /// <summary>
+    /// JSON array of placement constraints, e.g. ["node.labels.xibo==true"]
+    /// </summary>
+    [MaxLength(2000)]
+    public string? Constraints { get; set; }
+
+    [Required, MaxLength(500)]
+    public string TemplateRepoUrl { get; set; } = string.Empty;
+
+    [MaxLength(500)]
+    public string? TemplateRepoPat { get; set; }
+
+    public DateTime? TemplateLastFetch { get; set; }
+
+    [MaxLength(100)]
+    public string? TemplateCacheKey { get; set; }
+
+    public InstanceStatus Status { get; set; } = InstanceStatus.Deploying;
+
+    /// <summary>Encrypted Xibo admin username for API access.</summary>
+    [MaxLength(500)]
+    public string? XiboUsername { get; set; }
+
+    /// <summary>Encrypted Xibo admin password. Never logged; encrypted at rest.</summary>
+    [MaxLength(1000)]
+    public string? XiboPassword { get; set; }
+
+    public XiboApiTestStatus XiboApiTestStatus { get; set; } = XiboApiTestStatus.Unknown;
+
+    public DateTime? XiboApiTestedAt { get; set; }
+
+    public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
+
+    public DateTime UpdatedAt { get; set; } = DateTime.UtcNow;
+
+    /// <summary>Soft delete marker.</summary>
+    public DateTime? DeletedAt { get; set; }
+
+    // ── CIFS / SMB credentials (per-instance) ─────────────────────────────
+
+    [MaxLength(200)]
+    public string? CifsServer { get; set; }
+
+    [MaxLength(500)]
+    public string? CifsShareBasePath { get; set; }
+
+    [MaxLength(200)]
+    public string? CifsUsername { get; set; }
+
+    /// <summary>Encrypted CIFS password. Never logged; encrypted at rest.</summary>
+    [MaxLength(1000)]
+    public string? CifsPassword { get; set; }
+
+    [MaxLength(500)]
+    public string? CifsExtraOptions { get; set; }
+
+    /// <summary>ID of the SshHost this instance is deployed to.</summary>
+    public Guid? SshHostId { get; set; }
+
+    [ForeignKey(nameof(SshHostId))]
+    public SshHost? SshHost { get; set; }
+
+    public ICollection<OperationLog> OperationLogs { get; set; } = new List<OperationLog>();
+}