fix: memory leaks — cleanup timers on unmount, tighten speech queue, fix isOwner reactivity

- FightViewer: track deferred speechSynthesis.cancel() timer, clear on unmount
- BotProfilePage: change isOwner from ref to computed for reactive login state
- sounds.ts: tighten speech queue depth cap from 3 to 2

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

frontend/src/pages/BotProfilePage.vue

@@ -76,7 +76,6 @@ const showChoose = ref(false)
 const waitingFighters = ref<QueueEntry[]>([])
 let pollHandle: ReturnType<typeof setInterval> | null = null
 
-const isOwner = ref(false)
 const loadError = ref('')
 const fightError = ref('')
 const showCustomize = ref(false)
@@ -102,6 +101,8 @@ const ARCHETYPES = [
   'broom_man',
 ]
 
+const isOwner = computed(() => isLoggedIn.value && nostrBot.value?.name === botName)
+
 const custForm = reactive({
   archetype: '',
   primaryColor: '#3388cc',
@@ -216,9 +217,6 @@ onMounted(async () => {
   }
   isLoading.value = false
 
-  // Check ownership
-  isOwner.value = isLoggedIn.value && nostrBot.value?.name === botName
-
   // Poll queue for "choose your fight"
   pollQueue()
   pollHandle = setInterval(pollQueue, 4000)