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/Common/EntityTests.cs

@@ -0,0 +1,58 @@
+using PnvPanel.Domain.Common;
+using Xunit;
+
+namespace PnvPanel.Domain.Tests.Common;
+
+public class EntityTests
+{
+    private sealed class FakeEntityA : Entity
+    {
+        public FakeEntityA(Guid id) => Id = id;
+    }
+
+    private sealed class FakeEntityB : Entity
+    {
+        public FakeEntityB(Guid id) => Id = id;
+    }
+
+    [Fact]
+    public void Equals_SameTypeAndId_ReturnsTrue()
+    {
+        var id = Guid.NewGuid();
+        var a = new FakeEntityA(id);
+        var b = new FakeEntityA(id);
+
+        Assert.Equal(a, b);
+        Assert.True(a == b);
+    }
+
+    [Fact]
+    public void Equals_DifferentTypesSameId_ReturnsFalse()
+    {
+        var id = Guid.NewGuid();
+        var a = new FakeEntityA(id);
+        var b = new FakeEntityB(id);
+
+        Assert.False(a.Equals(b));
+    }
+
+    [Fact]
+    public void Equals_SameTypeDifferentId_ReturnsFalse()
+    {
+        var a = new FakeEntityA(Guid.NewGuid());
+        var b = new FakeEntityA(Guid.NewGuid());
+
+        Assert.NotEqual(a, b);
+        Assert.True(a != b);
+    }
+
+    [Fact]
+    public void GetHashCode_SameTypeAndId_AreEqual()
+    {
+        var id = Guid.NewGuid();
+        var a = new FakeEntityA(id);
+        var b = new FakeEntityA(id);
+
+        Assert.Equal(a.GetHashCode(), b.GetHashCode());
+    }
+}