feat(mission-control): give the list handler its own review task

"Let Claude handle it" now creates one ClaudeDo task per run to host the
ConPTY session (Idle/IsManual, never queued) instead of an untracked
ad-hoc tile, so the run has a real title, diff, and review outcome.
Since the handler merges its own changes straight into the list's
working dir, the task never gets a WorktreeEntity; its review range
lives as new HandlerBaseCommit/HandlerHeadCommit columns on TaskEntity
instead, reusing the existing commit-range diff machinery and keeping
it out of the worktrees overview entirely.

src/ClaudeDo.Worker/Runner/Interfaces/IInteractiveLaunchSpecService.cs

@@ -34,4 +34,12 @@ public interface IInteractiveLaunchSpecService
     /// Throws KeyNotFoundException if the list doesn't exist; InvalidOperationException if
     /// taskIds is empty or the list has no existing working directory.</summary>
     Task<LaunchSpec> BuildForMergeHelperAsync(IReadOnlyList<string> taskIds, string listId, CancellationToken ct);
+
+    /// <summary>Creates the ClaudeDo task that hosts a list-handler run (Mission Control's
+    /// "Let Claude handle it") and stamps the list repo's current HEAD as the review range's
+    /// base commit (see TaskEntity.HandlerBaseCommit). Returns the new task's id. Throws
+    /// KeyNotFoundException if the list doesn't exist; InvalidOperationException if taskIds
+    /// is empty or the list has no existing working directory.</summary>
+    Task<string> CreateMergeHelperTaskAsync(
+        IReadOnlyList<string> taskIds, string listId, string title, string descriptionHeader, CancellationToken ct);
 }