refactor(worker): single parent-advance path for planning + improvement

Collapse TryCompleteParentAsync (planning -> Done) and
TryAdvanceImprovementParentAsync (improvement -> WaitingForReview) into one
TryAdvanceParentAsync that surfaces any WaitingForChildren parent for review
once all children are terminal. Planning parents no longer auto-complete.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/ClaudeDo.Data/Repositories/TaskRepository.cs

@@ -474,32 +474,5 @@ public sealed class TaskRepository
         return chainIds.Count;
     }
 
-    public async Task TryCompleteParentAsync(
-        string parentId,
-        CancellationToken ct = default)
-    {
-        var parent = await _context.Tasks.AsNoTracking().FirstOrDefaultAsync(t => t.Id == parentId, ct);
-        if (parent is null || parent.PlanningPhase != PlanningPhase.Finalized) return;
-
-        var children = await _context.Tasks
-            .Where(t => t.ParentTaskId == parentId)
-            .Select(t => t.Status)
-            .ToListAsync(ct);
-
-        if (children.Count == 0) return;
-
-        bool allTerminal = children.All(s => s == TaskStatus.Done || s == TaskStatus.Failed);
-        if (!allTerminal) return;
-
-        bool anyFailed = children.Any(s => s == TaskStatus.Failed);
-        var finalStatus = anyFailed ? TaskStatus.Failed : TaskStatus.Done;
-        var finishedAt = DateTime.UtcNow;
-        await _context.Tasks
-            .Where(t => t.Id == parentId)
-            .ExecuteUpdateAsync(s => s
-                .SetProperty(t => t.Status, finalStatus)
-                .SetProperty(t => t.FinishedAt, finishedAt), ct);
-    }
-
     #endregion
 }