Default: active facts only (`valid_to IS NULL`). Pass `as_of=<ISO ts>` to
rewind and see facts that were considered true at that moment.

Args:
    subject_id: Filter by subject entity id.
    predicate: Filter by exact predicate string.
    active_only: Only active facts (ignored when `as_of` is set).
    as_of: ISO-8601 timestamptz — time-machine cutoff.
    limit: Max rows (1-200).
    memory_id: Target memory id (auto-resolved if omitted).
    api_key: Bearer token for authentication.