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/Repositories/ListRepository.cs

@@ -33,7 +33,19 @@ public sealed class ListRepository
 
     public async Task<List<ListEntity>> GetAllAsync(CancellationToken ct = default)
     {
-        return await _context.Lists.OrderBy(l => l.CreatedAt).ToListAsync(ct);
+        return await _context.Lists.OrderBy(l => l.SortOrder).ThenBy(l => l.CreatedAt).ToListAsync(ct);
+    }
+
+    public async Task ReorderAsync(IReadOnlyList<string> orderedListIds, CancellationToken ct = default)
+    {
+        var idSet = orderedListIds.ToHashSet();
+        var entities = await _context.Lists.Where(l => idSet.Contains(l.Id)).ToListAsync(ct);
+        for (int i = 0; i < orderedListIds.Count; i++)
+        {
+            var e = entities.FirstOrDefault(x => x.Id == orderedListIds[i]);
+            if (e is not null) e.SortOrder = i;
+        }
+        await _context.SaveChangesAsync(ct);
     }
 
     public async Task<ListConfigEntity?> GetConfigAsync(string listId, CancellationToken ct = default)