feat(data): persist max_turns in list and task repositories

Add MaxTurns to ListRepository.SetConfigAsync upsert branch and
TaskRepository.UpdateAgentSettingsAsync; fix positional CancellationToken
call in ConfigMcpTools. Covered by MaxTurnsRoundTripTests (2 tests).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/ClaudeDo.Data/Repositories/ListRepository.cs

@@ -65,6 +65,7 @@ public sealed class ListRepository
             existing.Model = config.Model;
             existing.SystemPrompt = config.SystemPrompt;
             existing.AgentPath = config.AgentPath;
+            existing.MaxTurns = config.MaxTurns;
         }
         await _context.SaveChangesAsync(ct);
     }

src/ClaudeDo.Data/Repositories/TaskRepository.cs

@@ -159,6 +159,7 @@ public sealed class TaskRepository
         string? model,
         string? systemPrompt,
         string? agentPath,
+        int? maxTurns = null,
         CancellationToken ct = default)
     {
         await _context.Tasks
@@ -166,7 +167,8 @@ public sealed class TaskRepository
             .ExecuteUpdateAsync(s => s
                 .SetProperty(t => t.Model, model)
                 .SetProperty(t => t.SystemPrompt, systemPrompt)
-                .SetProperty(t => t.AgentPath, agentPath), ct);
+                .SetProperty(t => t.AgentPath, agentPath)
+                .SetProperty(t => t.MaxTurns, maxTurns), ct);
     }
 
     #endregion