[caigee-cmd]

Stacked on #359 (base feat/overview-stats). Frontend only.

Drill-down

• Rows in Top models, Top accounts and the error mix now link to /logs?model=|account=|error_kind=&from=&to=. from/to come from the overview's current stats window (window.from/to in the stats response).
• Provider rows are not clickable because /api/logs/requests has no provider filter. The handler in internal/console/logs.go accepts account, status, error_kind, model, id, q, from, to, stream, limit, offset.
• Unknown or unassigned rows and error kinds missing from the logs page's error_kind select are not linked.
• Dragging across TrafficChart draws a recharts ReferenceArea. On mouse-up it opens the logs page for [first bucket, last bucket + step).
• LogsPage reads status, account, model, error_kind, stream, id, range, from, to from the URL. It updates the URL (replace) when its filters change, and updates the filters when the URL changes (back/forward).
• The logs picker works in whole minutes and rounds the end up to :59.999. Drill-down links pass the end as one minute before its minute ceiling, so the range comes out exact after that rounding.

Time window

• The window options are now 1h, 24h, 7d, 30d and custom. Custom uses a shared TimeRangePicker that was pulled out of LogsPage (HeroUI DateRangePicker + RangeCalendar).
• The backend NormalizeStatsHours only accepts hours=1|24|168, so 30d and custom send from/to as RFC 3339 UTC. ParseQueryTime accepts that format.
• Stats refresh quietly every 30s (no skeleton; errors during a background refresh are ignored). A pause/play icon button stops the refresh. No refresh runs while document.hidden, and one catch-up refresh runs when the tab becomes visible again.
• The chart's line draw-in now plays once per mount, so background refreshes don't replay it.
• The recharts focus outline on the plot is removed.