metrics_daily.spend_usd is the co-op-wide total and deliberately spans every
team, operators included — the numbers were already right. What was missing
was a way to tell how much of that total is the co-op's OWN usage, so a
member-facing chart could not be misread as member-only activity.
Adds metrics_daily.operator_spend_usd: the per-day portion of spend_usd that
belongs to the accounts in OPERATOR_EMAILS (teams aliased member:<email>, like
anyone else). NULL = not measured (never a confident 0), mirroring spend_usd.
- metrics_snapshot.py: operator_spend_by_day() + write it on snapshot/backfill
- app/main.py: expose it in metrics_series (so /broker/metrics and
/admin/metrics/series carry it), and add operator_spend /
operator_all_time_spend to /admin/overview totals as the explicit breakout
of total_spend / total_all_time_spend.
spend_usd and every existing column are untouched.