feat(ui): list reordering, quick actions, and resizable modals

- Drag-to-reorder user lists in the sidebar, persisted via a new
  list sort_order column (AddListSortOrder migration, backfilled by
  creation time) and ListRepository.ReorderAsync
- "Open in Explorer" / "Open in Terminal" context-menu actions on lists
- "Clear all completed" button on the Tasks island
- Inline-edit subtask titles (empty text deletes the step) and
  click-to-copy task ID in the Details island
- Make modal and planning windows resizable (BorderOnly decorations
  with min sizes) instead of fixed-size borderless

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

src/ClaudeDo.Data/Configuration/ListEntityConfiguration.cs

@@ -16,6 +16,9 @@ public class ListEntityConfiguration : IEntityTypeConfiguration<ListEntity>
         builder.Property(l => l.CreatedAt).HasColumnName("created_at").IsRequired();
         builder.Property(l => l.WorkingDir).HasColumnName("working_dir");
         builder.Property(l => l.DefaultCommitType).HasColumnName("default_commit_type").IsRequired().HasDefaultValue("chore");
+        builder.Property(l => l.SortOrder).HasColumnName("sort_order").IsRequired().HasDefaultValue(0);
+
+        builder.HasIndex(l => l.SortOrder).HasDatabaseName("idx_lists_sort");
 
         builder.HasOne(l => l.Config)
             .WithOne(c => c.List)