fix: KAPLAY scene init robustness — wait for layout, catch errors

- FightViewer: wrap createFightScene in try/catch so scene failures
  don't crash every subsequent playRound call
- FightViewer: wait for container to have non-zero dimensions before
  creating canvas (prevents 0x0 canvas causing sprite load failures)
- FightViewer: graceful log-only fallback when scene init fails
- FightPage: same dimension-wait and try/catch for initLiveScene
- Fallback canvas dimensions (800x500) when container not yet laid out

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

frontend/src/pages/FightPage.vue

@@ -305,21 +305,30 @@ async function initLiveScene() {
 
   const container = liveCanvas.value.parentElement
   if (container) {
+    // Wait for container to have dimensions
+    for (let i = 0; i < 10 && (!container.clientWidth || !container.clientHeight); i++) {
+      await new Promise(r => requestAnimationFrame(r))
+    }
     const oldCanvas = liveCanvas.value
     const newCanvas = document.createElement('canvas')
     newCanvas.className = oldCanvas.className
-    newCanvas.width = container.clientWidth
-    newCanvas.height = container.clientHeight
+    newCanvas.width = container.clientWidth || 800
+    newCanvas.height = container.clientHeight || 500
     oldCanvas.replaceWith(newCanvas)
     liveCanvas.value = newCanvas
   }
 
-  liveScene = await createFightScene({
-    canvas: liveCanvas.value,
-    botA: { name: data.botA.name, seed: data.botA.avatarSeed || data.botA.name, tier: data.botA.tier, archetype: data.botA.archetype, customization: data.botA.customization, wins: data.botA.wins, losses: data.botA.losses },
-    botB: { name: data.botB.name, seed: data.botB.avatarSeed || data.botB.name, tier: data.botB.tier, archetype: data.botB.archetype, customization: data.botB.customization, wins: data.botB.wins, losses: data.botB.losses },
-    arena: data.arena,
-  })
+  try {
+    liveScene = await createFightScene({
+      canvas: liveCanvas.value,
+      botA: { name: data.botA.name, seed: data.botA.avatarSeed || data.botA.name, tier: data.botA.tier, archetype: data.botA.archetype, customization: data.botA.customization, wins: data.botA.wins, losses: data.botA.losses },
+      botB: { name: data.botB.name, seed: data.botB.avatarSeed || data.botB.name, tier: data.botB.tier, archetype: data.botB.archetype, customization: data.botB.customization, wins: data.botB.wins, losses: data.botB.losses },
+      arena: data.arena,
+    })
+  } catch (err) {
+    console.error('[FightPage] createFightScene failed:', err)
+    liveScene = null
+  }
 
   liveSceneReady.value = true