Power panel: show live draw in watts and the top consumers

[vinceferro]

Wish

The stock power panel shows battery %, time left and profile switching — but not what the machine is actually drawing right now, nor which processes are responsible.

Proposal

Two additions to panels/power:

1. Live draw in the panel (and optionally the pill): read battery flow from /sys/class/power_supply (power_now, or current_now × voltage_now — on Apple Silicon/Asahi macsmc-battery reports the latter; UPower energy-rate as fallback). Display signed watts: -33 W discharging, +18 W charging, with color thresholds (green/yellow/red).

2. Top consumers section: sample /proc/[0-9]*/stat jiffies on a timer (1 s while the panel is open), diff snapshots, and list the top 5 processes by CPU share of total jiffies. When the draw is known, attribute per-process watts proportionally (no RAPL on Asahi, so share × measured flow is the honest estimate — the list roughly sums to the battery rate). A multi-threaded process can legitimately exceed 100%.

Working reference: I run this as a clone of the stock plugin — ~80 lines of QML + a small sampling script, no extra processes. The sampler logic and the jiffies-diff math are self-contained and portable.

Happy to turn it into a PR against plugins/panels/power if there is interest.