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/src/PnvPanel.Domain/Configs/TrafficSample.cs

@@ -0,0 +1,29 @@
+namespace PnvPanel.Domain.Configs;
+
+/// <summary>
+/// Точка истории трафика. Id — long (не Guid, как у Entity) — таблица растёт быстро,
+/// авто-инкремент компактнее для высокочастотной записи. TTL-ретеншн — см. TrafficRetentionService.
+/// </summary>
+public sealed class TrafficSample
+{
+    public long Id { get; private set; }
+    public Guid ConfigId { get; private set; }
+    public DateTimeOffset Timestamp { get; private set; }
+    public long UpBytes { get; private set; }
+    public long DownBytes { get; private set; }
+
+    private TrafficSample()
+    {
+    }
+
+    public static TrafficSample Create(Guid configId, DateTimeOffset timestamp, long upBytes, long downBytes)
+    {
+        return new TrafficSample
+        {
+            ConfigId = configId,
+            Timestamp = timestamp,
+            UpBytes = upBytes,
+            DownBytes = downBytes,
+        };
+    }
+}