feat(worker): surface task numbers in MCP tool return payloads

Adds Number alongside every task id in External/'s DTOs -- the two
central mappers (ToDto/ToRefDto -> TaskDto/TaskRefDto) plus every
DTO that carries a bare task id and bypasses them (batch results,
queue state, wait-for-change, config, attachments, handoff,
lifecycle, merge-preview-set, worktree list). Input resolution
(#123 as an argument) stays for slice 3.

src/ClaudeDo.Worker/External/LifecycleMcpTools.cs

@@ -6,7 +6,7 @@ using TaskStatus = ClaudeDo.Data.Models.TaskStatus;
 
 namespace ClaudeDo.Worker.External;
 
-public sealed record ResetFailedTaskResult(bool Reset, string TaskId);
+public sealed record ResetFailedTaskResult(bool Reset, string TaskId, int Number);
 
 [McpServerToolType]
 public sealed class LifecycleMcpTools
@@ -34,6 +34,6 @@ public sealed class LifecycleMcpTools
             throw new InvalidOperationException($"Task {taskId} is {task.Status}, not Failed. Only failed tasks can be reset via this tool.");
 
         await _reset.ResetAsync(taskId, cancellationToken);
-        return new ResetFailedTaskResult(true, taskId);
+        return new ResetFailedTaskResult(true, taskId, task.Number);
     }
 }