Implement IDisposable for scheduled tasks

Added IDisposable interface to scheduled task classes to ensure proper resource cleanup. Specifically, added dispose methods to release timers and cancellation tokens where applicable.

src/modules/Elsa.Scheduling/ScheduledTasks/ScheduledCronTask.cs

@@ -10,7 +10,7 @@ namespace Elsa.Scheduling.ScheduledTasks;
 /// <summary>
 /// A task that is scheduled using a given cron expression.
 /// </summary>
-public class ScheduledCronTask : IScheduledTask
+public class ScheduledCronTask : IScheduledTask, IDisposable
 {
     private readonly ISystemClock _systemClock;
     private readonly ILogger _logger;
@@ -97,4 +97,10 @@ public class ScheduledCronTask : IScheduledTask
             if (!cancellationToken.IsCancellationRequested) Schedule();
         };
     }
+
+    void IDisposable.Dispose()
+    {
+        _timer?.Dispose();
+        _cancellationTokenSource.Dispose();
+    }
 }

src/modules/Elsa.Scheduling/ScheduledTasks/ScheduledRecurringTask.cs

@@ -9,7 +9,7 @@ namespace Elsa.Scheduling.ScheduledTasks;
 /// <summary>
 /// A scheduled recurring task.
 /// </summary>
-public class ScheduledRecurringTask : IScheduledTask
+public class ScheduledRecurringTask : IScheduledTask, IDisposable
 {
     private readonly ITask _task;
     private readonly ISystemClock _systemClock;
@@ -87,4 +87,10 @@ public class ScheduledRecurringTask : IScheduledTask
             if (!cancellationToken.IsCancellationRequested) Schedule();
         };
     }
+
+    void IDisposable.Dispose()
+    {
+        _cancellationTokenSource.Dispose();
+        _timer?.Dispose();
+    }
 }

src/modules/Elsa.Scheduling/ScheduledTasks/ScheduledSpecificInstantTask.cs

@@ -9,7 +9,7 @@ namespace Elsa.Scheduling.ScheduledTasks;
 /// <summary>
 /// A task that is scheduled to execute at a specific instant.
 /// </summary>
-public class ScheduledSpecificInstantTask : IScheduledTask
+public class ScheduledSpecificInstantTask : IScheduledTask, IDisposable
 {
     private readonly ITask _task;
     private readonly ISystemClock _systemClock;
@@ -58,4 +58,10 @@ public class ScheduledSpecificInstantTask : IScheduledTask
                 await commandSender.SendAsync(new RunScheduledTask(_task), cancellationToken);
         };
     }
+
+    void IDisposable.Dispose()
+    {
+        _cancellationTokenSource.Dispose();
+        _timer?.Dispose();
+    }
 }

src/modules/Elsa.Workflows.Core/Contexts/ActivityExecutionContext.cs

@@ -17,7 +17,7 @@ namespace Elsa.Workflows;
 /// Represents the context of an activity execution.
 /// </summary>
 [PublicAPI]
-public partial class ActivityExecutionContext : IExecutionContext
+public partial class ActivityExecutionContext : IExecutionContext, IDisposable
 {
     private readonly ISystemClock _systemClock;
     private readonly List<Bookmark> _bookmarks = new();
@@ -676,4 +676,10 @@ public partial class ActivityExecutionContext : IExecutionContext
     {
         return ExpressionExecutionContext.TryGetBlock(locationBlockReference, out var memoryBlock) ? memoryBlock : default;
     }
+
+    void IDisposable.Dispose()
+    {
+        _cancellationRegistration.Dispose();
+        _cancellationTokenSource.Dispose();
+    }
 }