perf: fight replay memory leak fixes

Replace 32 bare setTimeout calls with tracked timeouts across all fight
modules (effects, entrances, finishers, choreographies). All timers are
now registered in cleanupTimers Set and cleared on scene destroy.

Enhanced destroy() to also clean up active speech bubbles and explicitly
destroy all remaining game objects before k.quit().

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/game/FightScene.ts

@@ -386,7 +386,7 @@ export async function createFightScene(config: FightSceneConfig) {
       })
       lines.push(line)
     }
-    setTimeout(() => { lines.forEach(l => { if (l.exists()) l.destroy() }) }, duration * 1000)
+    trackedTimeout(() => { lines.forEach(l => { if (l.exists()) l.destroy() }) }, duration * 1000)
   }
 
   // Flash the whole screen
@@ -1802,7 +1802,7 @@ export async function createFightScene(config: FightSceneConfig) {
   const choreoCtx: ChoreoContext = {
     k, W, H, GROUND_Y, FRAME_SIZE, theme,
     safeColor: (color: string) => safeColor(k, color),
-    trackedInterval, clearTracked,
+    trackedTimeout, trackedInterval, clearTracked,
     spawnSparks, spawnBulletHoles, spawnExhaust, spawnProjectile,
     spawnShockwave, screenFlash, impactFreeze, spawnAfterimages,
     glitchRGB, scanlineGlitch, dimensionalShift,
@@ -2041,7 +2041,7 @@ export async function createFightScene(config: FightSceneConfig) {
     else activeBubbleB = allEls
 
     // Fade out after duration
-    setTimeout(() => {
+    trackedTimeout(() => {
       allEls.forEach(el => {
         if (!el.exists()) return
         k.tween(el.opacity, 0, 0.35, (v) => { el.opacity = v }).then(() => {
@@ -2368,7 +2368,7 @@ export async function createFightScene(config: FightSceneConfig) {
     if (funnyAction === 0) {
       // Falls asleep, snaps awake
       for (let z = 0; z < 3; z++) {
-        setTimeout(() => {
+        trackedTimeout(() => {
           spawnEmoteText(judge.pos.x + 15, judge.pos.y - 20, 'Z', '#8888ff', 1.0)
         }, z * 400)
       }
@@ -3441,11 +3441,19 @@ export async function createFightScene(config: FightSceneConfig) {
       stopMusic()
       stopTalking('a')
       stopTalking('b')
+      // Destroy lingering speech bubbles
+      activeBubbleA.forEach(o => { if (o.exists()) o.destroy() })
+      activeBubbleB.forEach(o => { if (o.exists()) o.destroy() })
+      activeBubbleA.length = 0
+      activeBubbleB.length = 0
+      // Clear all tracked timers
       for (const id of cleanupTimers) {
         clearInterval(id)
         clearTimeout(id)
       }
       cleanupTimers.clear()
+      // Destroy all remaining game objects before quitting
+      try { k.get('*').forEach(o => { if (o.exists()) o.destroy() }) } catch {}
       k.quit()
     },
   }