fix(PPO_Bot): radar lock — use enemy_tracker width-lock, fix arctan2 arg order

Three bugs caused the radar to sweep continuously instead of locking:

1. run() loop set radar to Inf every tick, overwriting any lock
   → replaced with enemy_tracker.getRadarTurnRate()

2. onScannedBot used radarBearingTo() (math convention, east=0 CCW)
   → removed; run loop now handles radar via enemy_tracker

3. enemy_tracker.getRadarTurnRate() had arctan2(dx,dy) instead of
   arctan2(dy,dx) — introduced by fd22535; bearing was off by ~90°

Also relaxed stale-lock threshold from 2 to 8 ticks to survive
brief scan gaps without falling back to full sweep.

Added tools/battle_runner for automated 1v1 testing.

Result: 1303/1308 ticks with successful scan (was ~1 in 4).

PPO_Bot/PPO_Bot.nim

@@ -64,6 +64,9 @@ method onScannedBot*(bot: PPOBot, e: ScannedBotEvent) =
   bot.tracker.update(e.x, e.y, e.direction, e.speed, e.energy)
 
 method onRoundStarted*(bot: PPOBot, e: RoundStartedEvent) =
+  setAdjustGunForBodyTurn(true)
+  setAdjustRadarForBodyTurn(true)
+  setAdjustRadarForGunTurn(true)
   bot.tracker        = initEnemyTracker()
   bot.buffer         = initTrajectoryBuffer()
   bot.prevEnergy     = 0.0'f32
@@ -130,8 +133,7 @@ method run(bot: PPOBot) =
   while isRunning():
     bot.tracker.deadReckon()
 
-    setRadarTurnRate(bot.tracker.getRadarTurnRate(
-      getX(), getY(), getDirection(), getRadarDirection()))
+    setRadarTurnRate(bot.tracker.getRadarTurnRate(getX(), getY(), getDirection(), getRadarDirection()))
 
     let botData = BotStateData(
       x:           getX(),