Enhance documentation with new features: added dark/light/system theme support, instructions page, and application catalog. Updated API and domain model for app management and automatic migrations on startup. Improved frontend structure with new routes and features for user instructions and app management.

backend/src/PnvPanel.Infrastructure/Security/DataProtectionSecretProtector.cs

@@ -0,0 +1,20 @@
+using Microsoft.AspNetCore.DataProtection;
+using PnvPanel.Application.Common.Interfaces;
+
+namespace PnvPanel.Infrastructure.Security;
+
+internal sealed class DataProtectionSecretProtector : ISecretProtector
+{
+    private const string Purpose = "PnvPanel.NodeCredentials.v1";
+
+    private readonly IDataProtector _protector;
+
+    public DataProtectionSecretProtector(IDataProtectionProvider provider)
+    {
+        _protector = provider.CreateProtector(Purpose);
+    }
+
+    public string Protect(string plaintext) => _protector.Protect(plaintext);
+
+    public string Unprotect(string protectedValue) => _protector.Unprotect(protectedValue);
+}