vm_physics_charge(): per-beat slope into a per-VM carry, whole units pulled
from the rest of the live fleet in proportion to heat (conservative
vm_physics_transfer), rounding shortfall kept in the carry, no fleet_window
sample. Called from vm_tick() only for the switch-current VM. Closes G9:
a VM running its own mail on its own stack now heats up while it works.
Probe (reverted): baseline Hestia heat 0->0->0 over 71 beats (FAIL, proves
G9); with charge 0->11->23 at beats 15->51->86, identical on amd64/aarch64/
riscv64, conserved, PASS. Acceptance: dict_hash unchanged, WIREBIND relay 3.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
