Problem

Two issues affect the home load consumption history.

1. Timezone mismatch. While building the per-device consumption in the optimization loop, the 24h look-back window is created with a naive datetime.now(), but Home Assistant and the persistence layer return timezone-aware (UTC) timestamps. The comparison fails with:

   Error getting load history for device '...': can't compare offset-naive and offset-aware datetimes
   

   The same naive/aware mix affects the history purge cut-off.

2. Manual collection ignores the look-back window. When power points already exist for a device, a manual collection only fetches incrementally from the last stored point, ignoring the requested lookback_hours. Requesting e.g. 30 days returns only the few most recent points and never backfills internal gaps.

Expected

• History datetimes are consistently timezone-aware (UTC).
• A manual collection honours the requested look-back window and backfills missing data additively, without dropping already-stored points (bounded by Home Assistant's recorder retention).

Notes

The scheduled periodic collection stays incremental for efficiency.