Implement NotifyOnStatusChange feature for nodes and enhance Telegram notifications

- Added `NotifyOnStatusChange` property to the `Node` class and related DTOs to allow individual node configuration for status change notifications.
- Updated `NodeHealthCheckService` to send Telegram notifications to admins when a node's status changes, based on the new property.
- Enhanced the `ITelegramNotifier` interface with a method for notifying admins about node status changes.
- Modified the frontend to include a checkbox for `NotifyOnStatusChange` in the node editing dialog, allowing admins to easily configure this setting.
- Updated API documentation to reflect the new `notifyOnStatusChange` parameter in the node update endpoint.
- Added tests to ensure the correct behavior of the new feature and its integration with existing functionality.

backend/tests/PnvPanel.Application.Tests/Admin/Nodes/UpdateNodeCommandHandlerTests.cs

@@ -38,6 +38,7 @@ public class UpdateNodeCommandHandlerTests
             "https://node1-new.example.com",
             null,
             true,
+            false,
             null,
             null
         );
@@ -66,6 +67,7 @@ public class UpdateNodeCommandHandlerTests
             "https://node1.example.com",
             "eu",
             true,
+            false,
             null,
             null
         );
@@ -88,7 +90,7 @@ public class UpdateNodeCommandHandlerTests
 
         var handler = new UpdateNodeCommandHandler(dbContext, _gateway, _secretProtector, _currentUser);
 
-        var command = new UpdateNodeCommand(node.Id, "node-1", "not-a-uri", null, true, null, null);
+        var command = new UpdateNodeCommand(node.Id, "node-1", "not-a-uri", null, true, false, null, null);
 
         var result = await handler.Handle(command, CancellationToken.None);
 
@@ -117,6 +119,7 @@ public class UpdateNodeCommandHandlerTests
             "http://node1-new.example.com",
             null,
             true,
+            false,
             null,
             null
         );
@@ -147,6 +150,7 @@ public class UpdateNodeCommandHandlerTests
             "https://node1.example.com",
             null,
             true,
+            false,
             "new-admin",
             "new-password"
         );
@@ -175,6 +179,7 @@ public class UpdateNodeCommandHandlerTests
             "https://node1.example.com",
             null,
             true,
+            false,
             "new-admin",
             null
         );
@@ -187,6 +192,34 @@ public class UpdateNodeCommandHandlerTests
         _gateway.DidNotReceive().InvalidateClient(Arg.Any<Guid>());
     }
 
+    [Fact]
+    public async Task Handle_SetsNotifyOnStatusChange()
+    {
+        using var dbContext = InMemoryDbContextFactory.Create();
+        var node = SeedNode();
+        dbContext.Nodes.Add(node);
+        await dbContext.SaveChangesAsync(CancellationToken.None);
+        Assert.False(node.NotifyOnStatusChange);
+
+        var handler = new UpdateNodeCommandHandler(dbContext, _gateway, _secretProtector, _currentUser);
+
+        var command = new UpdateNodeCommand(
+            node.Id,
+            "node-1",
+            "https://node1.example.com",
+            null,
+            true,
+            true,
+            null,
+            null
+        );
+
+        var result = await handler.Handle(command, CancellationToken.None);
+
+        Assert.True(result.IsSuccess);
+        Assert.True(node.NotifyOnStatusChange);
+    }
+
     [Fact]
     public async Task Handle_WhenNodeNotFound_ReturnsNotFound()
     {
@@ -200,6 +233,7 @@ public class UpdateNodeCommandHandlerTests
             "https://node1.example.com",
             null,
             true,
+            false,
             null,
             null
         );

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

@@ -97,6 +97,19 @@ public class NodeTests
         Assert.True(node.IsEnabled);
     }
 
+    [Fact]
+    public void SetNotifyOnStatusChange_DefaultsFalse_AndCanBeToggled()
+    {
+        var node = Node.Register("Node", new Uri("https://example.com"), Credentials, null);
+        Assert.False(node.NotifyOnStatusChange);
+
+        node.SetNotifyOnStatusChange(true);
+        Assert.True(node.NotifyOnStatusChange);
+
+        node.SetNotifyOnStatusChange(false);
+        Assert.False(node.NotifyOnStatusChange);
+    }
+
     [Fact]
     public void UpdateStatus_SetsStatus()
     {