fix(repair): keep ebike at zone Y in test scene

Adds an opt-out 'snapToTerrain' prop on Ebike so the parked position
keeps the explicit Y supplied by callers instead of resolving against
the world terrain GLTF. TestMap passes snapToTerrain={false} since it
does not render the world terrain — without this the bike was being
positioned at the invisible terrain height, far above the test floor,
and looked missing.

src/world/debug/TestMap.tsx

@@ -241,7 +241,7 @@ export function TestMap({ onOctreeReady }: TestMapProps): React.JSX.Element {
               <RepairPlaygroundZoneMarker color={zone.color} />
             </group>
             {zone.mission === "ebike" ? (
-              <Ebike position={zone.position} />
+              <Ebike position={zone.position} snapToTerrain={false} />
             ) : null}
             <RepairGame mission={zone.mission} position={zone.position} />
           </group>