feat(worktrees): add GetOverviewAsync for overview modal

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

src/ClaudeDo.Worker/Worktrees/WorktreeOverviewRow.cs

@@ -0,0 +1,17 @@
+using ClaudeDo.Data.Models;
+using TaskStatus = ClaudeDo.Data.Models.TaskStatus;
+
+namespace ClaudeDo.Worker.Worktrees;
+
+public sealed record WorktreeOverviewRow(
+    string TaskId,
+    string TaskTitle,
+    TaskStatus TaskStatus,
+    string ListId,
+    string ListName,
+    string Path,
+    string BranchName,
+    WorktreeState State,
+    string? DiffStat,
+    DateTime CreatedAt,
+    bool PathExistsOnDisk);