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/Telegram/TelegramLinkTokenTests.cs

@@ -0,0 +1,59 @@
+using PnvPanel.Domain.Exceptions;
+using PnvPanel.Domain.Telegram;
+using Xunit;
+
+namespace PnvPanel.Domain.Tests.Telegram;
+
+public class TelegramLinkTokenTests
+{
+    [Fact]
+    public void Create_IsValidBeforeConsumptionOrExpiry()
+    {
+        var userId = Guid.NewGuid();
+
+        var token = TelegramLinkToken.Create(userId, TimeSpan.FromMinutes(10));
+
+        Assert.Equal(userId, token.UserId);
+        Assert.True(token.IsValid);
+        Assert.Null(token.ConsumedAt);
+        Assert.False(string.IsNullOrWhiteSpace(token.Token));
+    }
+
+    [Fact]
+    public void Create_GeneratesUniqueTokens()
+    {
+        var a = TelegramLinkToken.Create(Guid.NewGuid(), TimeSpan.FromMinutes(10));
+        var b = TelegramLinkToken.Create(Guid.NewGuid(), TimeSpan.FromMinutes(10));
+
+        Assert.NotEqual(a.Token, b.Token);
+    }
+
+    [Fact]
+    public void Consume_WhenValid_SetsConsumedAtAndInvalidates()
+    {
+        var token = TelegramLinkToken.Create(Guid.NewGuid(), TimeSpan.FromMinutes(10));
+
+        token.Consume();
+
+        Assert.NotNull(token.ConsumedAt);
+        Assert.False(token.IsValid);
+    }
+
+    [Fact]
+    public void Consume_WhenAlreadyConsumed_Throws()
+    {
+        var token = TelegramLinkToken.Create(Guid.NewGuid(), TimeSpan.FromMinutes(10));
+        token.Consume();
+
+        Assert.Throws<DomainException>(() => token.Consume());
+    }
+
+    [Fact]
+    public void Consume_WhenExpired_Throws()
+    {
+        var token = TelegramLinkToken.Create(Guid.NewGuid(), TimeSpan.Zero);
+
+        Assert.False(token.IsValid);
+        Assert.Throws<DomainException>(() => token.Consume());
+    }
+}