Avoid filtering loader queries by canonical user_id. Calling loaders with user_id=user_id introduces an exact-ID filter path that can drop valid legacy tasks: several loaders (e.g., load_due_market_trends_tasks) apply ...where task.user_id == user_id, but this commit also shifts discovery toward canonical IDs, so tasks persisted earlier with workspace-safe/sanitized IDs in the same per-user DB will no longer be returned and therefore never execute. Before this change, loaders were invoked as task_loader(db) and did not regress on mixed ID formats.
