maincloud metrics

the metrics pages are nice and useful but it isn't clear what the graphs are actually showing. some of them are showing the accumulated values per minute, some per 30 or 15 seconds and some have their time scale all over the place depending how the graph loaded.
for some i don't even know what to do with the value like the table storage being in mb but being calculated as GB-seconds in the energy usage.
i have one reducer that runs every 2 seconds and the graph shows it as 1.6 to 2 TPS with a time scale step of 30 seconds. is that an accumulated value too? how does it get to 2TPS? at best this is VERY misleading.

besides that, why aren't the metrics stored in a st_metrics (event) table that the dashboard can just load from the clog or at least get as subcription. this also would allow the standalone version to have metrics too.

Requested by @xDovos via the SpacetimeDB site.

Start at the maincloud metrics pages and trace how graph values, time-scale steps, reducer rates, table storage, and energy usage are calculated and displayed. Compare the behavior across the mentioned intervals and investigate the proposed st_metrics event-table path for dashboard and standalone metrics. Done means the metric units and aggregation windows are consistent and clearly defined, with the storage approach scoped.