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.Desktop/Services/SshDockerSecretsService.cs

@@ -0,0 +1,140 @@
+using System.Globalization;
+using System.Text;
+using Microsoft.Extensions.Logging;
+using OTSSignsOrchestrator.Core.Models.Entities;
+using OTSSignsOrchestrator.Core.Services;
+
+namespace OTSSignsOrchestrator.Desktop.Services;
+
+/// <summary>
+/// Docker Swarm secrets management over SSH.
+/// Uses docker CLI commands executed remotely instead of Docker.DotNet.
+/// </summary>
+public class SshDockerSecretsService : IDockerSecretsService
+{
+    private readonly SshConnectionService _ssh;
+    private readonly ILogger<SshDockerSecretsService> _logger;
+    private SshHost? _currentHost;
+
+    public SshDockerSecretsService(SshConnectionService ssh, ILogger<SshDockerSecretsService> logger)
+    {
+        _ssh = ssh;
+        _logger = logger;
+    }
+
+    public void SetHost(SshHost host) => _currentHost = host;
+    public SshHost? CurrentHost => _currentHost;
+
+    public async Task<(bool Created, string SecretId)> EnsureSecretAsync(string name, string value, bool rotate = false)
+    {
+        EnsureHost();
+
+        _logger.LogInformation("Ensuring secret exists via SSH: {SecretName}", name);
+
+        // Check if secret already exists
+        var existing = await FindSecretAsync(name);
+
+        if (existing != null && !rotate)
+        {
+            _logger.LogDebug("Secret already exists: {SecretName} (id={SecretId})", name, existing.Value.id);
+            return (false, existing.Value.id);
+        }
+
+        if (existing != null && rotate)
+        {
+            _logger.LogInformation("Rotating secret via SSH: {SecretName} (old id={SecretId})", name, existing.Value.id);
+            await _ssh.RunCommandAsync(_currentHost!, $"docker secret rm {name}");
+        }
+
+        // Create secret via stdin
+        var safeValue = value.Replace("'", "'\\''");
+        var (exitCode, stdout, stderr) = await _ssh.RunCommandAsync(
+            _currentHost!, $"printf '%s' '{safeValue}' | docker secret create {name} -");
+
+        if (exitCode != 0)
+        {
+            _logger.LogError("Failed to create secret via SSH: {SecretName} | error={Error}", name, stderr);
+            return (false, string.Empty);
+        }
+
+        var secretId = stdout.Trim();
+        _logger.LogInformation("Secret created via SSH: {SecretName} (id={SecretId})", name, secretId);
+        return (true, secretId);
+    }
+
+    public async Task<List<SecretListItem>> ListSecretsAsync()
+    {
+        EnsureHost();
+
+        var (exitCode, stdout, _) = await _ssh.RunCommandAsync(
+            _currentHost!, "docker secret ls --format '{{.ID}}\\t{{.Name}}\\t{{.CreatedAt}}'");
+
+        if (exitCode != 0 || string.IsNullOrWhiteSpace(stdout))
+            return new List<SecretListItem>();
+
+        return stdout
+            .Split('\n', StringSplitOptions.RemoveEmptyEntries)
+            .Select(line =>
+            {
+                var parts = line.Split('\t', 3);
+                return new SecretListItem
+                {
+                    Id = parts.Length > 0 ? parts[0].Trim() : "",
+                    Name = parts.Length > 1 ? parts[1].Trim() : "",
+                    CreatedAt = parts.Length > 2 && DateTime.TryParse(parts[2].Trim(), CultureInfo.InvariantCulture, DateTimeStyles.None, out var dt)
+                        ? dt
+                        : DateTime.MinValue
+                };
+            })
+            .ToList();
+    }
+
+    public async Task<bool> DeleteSecretAsync(string name)
+    {
+        EnsureHost();
+
+        var existing = await FindSecretAsync(name);
+        if (existing == null)
+        {
+            _logger.LogDebug("Secret not found for deletion: {SecretName}", name);
+            return true; // idempotent
+        }
+
+        var (exitCode, _, stderr) = await _ssh.RunCommandAsync(_currentHost!, $"docker secret rm {name}");
+        if (exitCode != 0)
+        {
+            _logger.LogError("Failed to delete secret via SSH: {SecretName} | error={Error}", name, stderr);
+            return false;
+        }
+
+        _logger.LogInformation("Secret deleted via SSH: {SecretName}", name);
+        return true;
+    }
+
+    private async Task<(string id, string name)?> FindSecretAsync(string name)
+    {
+        var (exitCode, stdout, _) = await _ssh.RunCommandAsync(
+            _currentHost!, $"docker secret ls --filter 'name={name}' --format '{{{{.ID}}}}\\t{{{{.Name}}}}'");
+
+        if (exitCode != 0 || string.IsNullOrWhiteSpace(stdout))
+            return null;
+
+        var line = stdout.Split('\n', StringSplitOptions.RemoveEmptyEntries)
+            .FirstOrDefault(l =>
+            {
+                var parts = l.Split('\t', 2);
+                return parts.Length > 1 && string.Equals(parts[1].Trim(), name, StringComparison.OrdinalIgnoreCase);
+            });
+
+        if (line == null) return null;
+
+        var p = line.Split('\t', 2);
+        return (p[0].Trim(), p[1].Trim());
+    }
+
+    private void EnsureHost()
+    {
+        if (_currentHost == null)
+            throw new InvalidOperationException("No SSH host configured. Call SetHost() before using Docker secrets.");
+    }
+}