chore(prototype): point probe header at the position-flip ticket

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

mod/content/overtake_probe.script.tl

@@ -1,5 +1,5 @@
--- PROTOTYPE (tickets "Probe vehicle data and native passing in game", "Can rebuilding a road segment move a passer
--- past its blocker?"): throwaway, lives only on branch prototype/vehicle-probe.
+-- PROTOTYPE (ticket "Can a script swap the positions of a follower and its leader?"): throwaway,
+-- lives only on branch prototype/vehicle-probe.
 -- Engine thread: every INTERVAL it logs every player-owned road vehicle (segment, lane, position, speed).
 -- GUI thread: EXPERIMENT flipping the positions of a follower and its leader (see below).
 -- Earlier experiments (timeToIgnore, engine-side jump, set-line, segment rebuild) are in git history and