fix(prompts): correct the list-handler wait cap and wait through WaitingForChildren

The execute prompt told the handler to wait with timeoutSeconds up to 170 -- a
leftover from the retired MCP_TOOL_TIMEOUT=200000ms era. The real server-side
clamp is TaskWaitMcpTools.MaxTimeoutSeconds = 900 and every launcher sets
930000ms, so the handler was making ~5x the wait_for_task_change calls it needed
and burning turns on re-waiting.

It also never passed treatWaitingForChildrenAsBusy, and only waited on ids that
were Queued or Running. A task with children reports "changed" the moment it
reaches WaitingForChildren, so such a task both dropped out of the wait set and
signalled completion early -- the handler could reach review/merge while
children were still running.

tests/ClaudeDo.Data.Tests/PromptFilesTests.cs

@@ -143,6 +143,27 @@ public class PromptFilesTests
         Assert.DoesNotContain("run_task_now(", d);  // single override slot — must not batch-start
     }
 
+    [Fact]
+    public void DefaultFor_merge_helper_execute_waits_with_the_real_server_side_cap()
+    {
+        // TaskWaitMcpTools.MaxTimeoutSeconds is 900 and every ClaudeDo launcher sets
+        // MCP_TOOL_TIMEOUT=930000ms. The prompt used to say 170 -- a leftover from the retired
+        // 200000ms era -- which burned ~5x the turns on re-waiting.
+        var d = PromptFiles.DefaultFor(PromptKind.MergeHelperExecute);
+        Assert.Contains("timeoutSeconds 900", d);
+        Assert.DoesNotContain("170", d);
+    }
+
+    [Fact]
+    public void DefaultFor_merge_helper_execute_waits_through_waiting_for_children()
+    {
+        // Without the flag, a parent with children reports "changed" as soon as it reaches
+        // WaitingForChildren, so the handler would advance to review/merge while children run.
+        var d = PromptFiles.DefaultFor(PromptKind.MergeHelperExecute);
+        Assert.Contains("treatWaitingForChildrenAsBusy=true", d);
+        Assert.Contains("WaitingForChildren", d);
+    }
+
     [Fact]
     public void DefaultFor_merge_helper_execute_keeps_the_shared_checkout_git_guard()
     {