private/get_subaccount_value_history

wallet, when set, takes precedence over subaccount_id. The window is unix milliseconds; period is seconds and must be one the sampler's tables cover.

By-wallet lookups return every owned subaccount's samples, concatenated and tagged with subaccount_id — not a summed wallet total. Coverage is ragged by design: a subaccount contributes no entry for buckets in which it held nothing, rather than reporting a zero it never had. Callers plotting a wallet total must group by subaccount_id and carry each series forward.