A dockable editor panel (RunEnergyPanel, bolt icon) that surfaces the last on-device
run's MEASURED cost live: host energy over the session with its provenance, the real
accepted/prompt token counts, and the derived efficiency (µJ per accepted token,
tokens/sec) -- the same figures the session's efficiency/1 receipt seals. No other
editor shows the joules a run spent, because none measure it.
The agent run's completion path publishes RunMetrics via energy_panel::record_run
(reusing the already-computed session_uj + token totals + wall time -- no new
metering, so no risk to the Send background run path). The panel polls the published
metrics ~1x/s so a run that finishes while it's open updates without interaction.
Registered in zed.rs alongside the other panels.
Verified: agent_joule_panel + full app build; the app launches with the panel
registered and no init crash (control server responds).