Added a before/after prop->pos probe spanning all of chrTick (not just the
player), gated on the existing d243mProbeActive(). Checked four background
guards on Dam with different actiontypes/animations/positions: all show
~zero before/after gap, nothing like the player puppet's ~328-unit float
measured in M-172. Rules out "every chr's root joint sits above prop->pos by
design, normal rendering just hides it" -- normal chr rendering is correctly
grounded. Narrows the remaining lead to the player-specific bodyModel draw
call (bondview2.c, near the existing D243M: draw/f488write probes) versus
the generic chrRenderProp path every other chr uses. Diagnosis only, no
game-code changes. Capture archived at scratch/d173/ (gitignored, local).