Runner job metrics chart: steps align with chart and chart covers full job duration

Runner job metrics charts in the dashboard now align correctly with the job’s step timeline and cover the full duration of the job. Hovering a step highlights the matching section of the chart, and long-running jobs no longer have their metrics cut off partway through: the macOS runner step its clock via NTP before the job starts (so step timestamps and metric samples share one timeline), and the per-Pod SA token used by the in-VM metrics sampler is now minted with an 8h TTL instead of 1h (so even warm, long-running Pods keep posting samples for the whole job instead of expiring mid-run and producing a 401 that truncates the chart).