test(vehicle): a review shot, and the judge that proves the car is missing

Adds demo-vehicle to the camera list and the visual targets, plus shot 9 in
Screenshots/README.md - marked FAIL, because that is what it shows.

The vehicle is staged and runs: spawned at (-12950,-900,120), 9 visual panels attached,
panel 0 visible with a 238 cm extent, settled at Z 119 cm. The capture shows an empty road
with a soft shadow. Two checks disagree in a useful way: visual_loop --verify PASSES the
frame (it only tests size, blankness and tonal range, so a well-exposed empty road passes),
while judge_screenshot returns verdict=no confidence=1.0.

Strongest clue, recorded in TODO.md: a downward trace from the vehicle finds no ground at
all (ground at Z -9999), so the car sits over a surface without collision or inside
geometry - the shadow and the panels are not in the same place.

Diagnostics added along the way: mesh/visibility/bounds at BeginPlay, per-panel world
positions and extents, and the ground trace. The visual panels were also unhidden from the
physics mesh: SetVisibility(false, ...) hid them whether or not propagation was requested.

Tools/visual_targets.json

@@ -96,6 +96,16 @@
         "Art/reference/hollywood/el-capitan-facade-day-wikimedia-2009-10-27.jpg"
       ],
       "expect": "The player body mid-stride in profile: legs apart, arms counter-swinging, walking along the sidewalk"
+    },
+    {
+      "name": "demo-vehicle",
+      "shot": "Screenshots/demo/review-demo-vehicle.png",
+      "size": [
+        1920,
+        1080
+      ],
+      "references": [],
+      "expect": "A red sedan parked on the road seen from the front three-quarter: body, cabin, four wheels visible, sitting on the surface rather than floating or sunk"
     }
   ]
 }