Count each processor package once, never read a sleeping card, and give no reading for a reset counter (hq ADR 0255)

Intel shows some packages twice (MSR and MMIO), an AMD card's sensors wake it, and a
counter reset after resume read as thousands of watts. The loop's cadence and the bar
script's staleness are now tested, and the sampler running on every machine is said.

modules/power/README.md

@@ -57,8 +57,15 @@ module's process `mesh-power-draw` (`power draw`, as root) samples every 5 s and
 averaged rate, one line, to `/run/mesh-power/draw` (0644). The bar's script prints that line, and says
 `power not measured` when it is missing or older than 30 s. Graphics are counted honestly: an AMD
 device only when it has its own memory (an APU's integrated graphics report the whole package, which
-the counter already holds), and an NVIDIA device through `nvidia-smi` only while it is awake, so the
-bar never wakes a sleeping GPU.
+the counter already holds), and only while it is awake; an NVIDIA device through `nvidia-smi` only
+while it is awake, so the bar never wakes a sleeping GPU. Each package is counted once by its name:
+where Intel shows one twice (`intel-rapl:N` and `intel-rapl-mmio:N`), the first is read. A counter that
+gives more than 1000 W was reset, after a resume say, and that sample gives no reading.
+
+**The sampler runs wherever this module is assigned, servers included.** A server has the energy
+counter too, so conditioning it on `power-meter` would not keep it off one, and the mesh has no way yet
+to condition a resource on another seat (the bar) being held on the machine. It costs one process
+reading a few kernel files every five seconds (novox/hq ADR 0255 §9).
 
 ## Settings