fix(data): address code review findings

- Fix sort order regression in GetByListIdAsync (was descending, should be ascending)
- Restore WAL mode pragma (was silently dropped in EF migration)
- Add existing-DB compatibility shim in MigrateAndConfigure (baselines InitialCreate
  migration for databases created by the old schema.sql)
- Remove dead AddDbContext/AddScoped registrations from Worker (only IDbContextFactory
  is used by singleton consumers)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/ClaudeDo.Data/Repositories/TaskRepository.cs

@@ -38,7 +38,7 @@ public sealed class TaskRepository
     {
         return await _context.Tasks
             .Where(t => t.ListId == listId)
-            .OrderByDescending(t => t.CreatedAt)
+            .OrderBy(t => t.CreatedAt)
             .ToListAsync(ct);
     }