Add Telegram bot integration and enhance user management features

- Introduced Telegram.Bot package for bot functionality.
- Updated user management to include Telegram linking and blocking features.
- Enhanced activation request handling with notifications via Telegram.
- Added new database entities for Telegram link tokens and login requests.
- Implemented traffic synchronization for client stats in the XuiPanelGateway.
- Updated application structure to support new test projects and improved dependency injection for Telegram services.

backend/tests/PnvPanel.Domain.Tests/Nodes/NodeTests.cs

@@ -0,0 +1,94 @@
+using PnvPanel.Domain.Exceptions;
+using PnvPanel.Domain.Nodes;
+using Xunit;
+
+namespace PnvPanel.Domain.Tests.Nodes;
+
+public class NodeTests
+{
+    private static NodeCredentials Credentials => new("admin", "protected-secret");
+
+    [Fact]
+    public void Register_WithAbsoluteUri_CreatesEnabledUnknownStatusNode()
+    {
+        var node = Node.Register("Germany-1", new Uri("https://de1.example.com:2053"), Credentials, "Germany");
+
+        Assert.Equal("Germany-1", node.Name);
+        Assert.Equal("Germany", node.Location);
+        Assert.Equal(NodeStatus.Unknown, node.Status);
+        Assert.True(node.IsEnabled);
+        Assert.NotEqual(Guid.Empty, node.Id);
+    }
+
+    [Fact]
+    public void Register_WithRelativeUri_Throws()
+    {
+        var relativeUri = new Uri("de1.example.com", UriKind.Relative);
+
+        Assert.Throws<DomainException>(() => Node.Register("Germany-1", relativeUri, Credentials, null));
+    }
+
+    [Fact]
+    public void UpdateDetails_ChangesNameAndLocation()
+    {
+        var node = Node.Register("Old", new Uri("https://example.com"), Credentials, "Old location");
+
+        node.UpdateDetails("New", "New location");
+
+        Assert.Equal("New", node.Name);
+        Assert.Equal("New location", node.Location);
+    }
+
+    [Fact]
+    public void UpdateCredentials_ReplacesCredentials()
+    {
+        var node = Node.Register("Node", new Uri("https://example.com"), Credentials, null);
+        var newCredentials = new NodeCredentials("root", "new-protected-secret");
+
+        node.UpdateCredentials(newCredentials);
+
+        Assert.Equal(newCredentials, node.Credentials);
+    }
+
+    [Fact]
+    public void Disable_ThenEnable_TogglesIsEnabled()
+    {
+        var node = Node.Register("Node", new Uri("https://example.com"), Credentials, null);
+
+        node.Disable();
+        Assert.False(node.IsEnabled);
+
+        node.Enable();
+        Assert.True(node.IsEnabled);
+    }
+
+    [Fact]
+    public void UpdateStatus_SetsStatus()
+    {
+        var node = Node.Register("Node", new Uri("https://example.com"), Credentials, null);
+
+        node.UpdateStatus(NodeStatus.Online);
+
+        Assert.Equal(NodeStatus.Online, node.Status);
+    }
+
+    [Fact]
+    public void MarkSynced_SetsLastSyncAt()
+    {
+        var node = Node.Register("Node", new Uri("https://example.com"), Credentials, null);
+        Assert.Null(node.LastSyncAt);
+
+        node.MarkSynced();
+
+        Assert.NotNull(node.LastSyncAt);
+    }
+
+    [Fact]
+    public void NodeCredentials_ToString_RedactsPassword()
+    {
+        var text = Credentials.ToString();
+
+        Assert.DoesNotContain("protected-secret", text);
+        Assert.Contains("REDACTED", text);
+    }
+}