Task: Record the run statistics on the result

A result states when its run started and finished, how many bytes it read and wrote, and its peak memory, so the Jobs tab can show them.

• The result model and its SQL hold the five fields, nullable for runs in flight and for results written before the change.
• compute.v1.ops.submit_result carries the five fields and the handler stores them.
• The generated reads return them.

(Implementation strategy. Written when work starts; key decisions are distilled into the parent story's * Decisions at close, but the plan itself stays — it is the historical record of what we did.)

Every number this task claims about a tree, with the command that produced it and the commit it was measured at. A number without both is not a measurement, because a clean-up record describes a tree and trunk moves under a branch: a consumer count, a gate's component count and a suite's size all change with no code changing, and the reader of a bare number cannot tell which tree it came from. Where the raw output matters, put it in an evidence/ file beside the task and name that file in the Command column.

Manual QA scenarios (scaffolded via compass add test_scenario) that verify this task. Link new ones here as they're created; the scenario doc itself links back via its "Verifies task" field.