refactor: extract shared FightData interface to fight/types.ts

Move FightData, FightRound, FightBot, FightArenaInfo types from local
definitions in FightViewer.vue to shared fight/types.ts. Replace `any`
typing in HumanFightPage, FightPage, useFightPolling, and useFightCache
with proper typed interfaces. Fix null-safety guards exposed by typing.

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

frontend/src/pages/HumanFightPage.vue

@@ -3,13 +3,14 @@ import { ref, computed, onMounted, onUnmounted, nextTick } from 'vue'
 import { useRoute, useRouter } from 'vue-router'
 import { useNostr } from '../composables/useNostr'
 import FightViewer from '../components/FightViewer.vue'
+import type { FightData } from '../game/fight/types'
 
 const route = useRoute()
 const router = useRouter()
 const { bot: myBot, isLoggedIn } = useNostr()
 
 const fightId = ref(route.params.fightId as string)
-const fight = ref<any>(null)
+const fight = ref<FightData | null>(null)
 const phase = ref<'waiting' | 'challenge' | 'submitted' | 'between' | 'finished' | 'replay' | 'error'>('waiting')
 const error = ref('')
 
@@ -198,7 +199,7 @@ async function loadFight() {
         opponentName.value = enemy?.name || 'Unknown'
       }
       if (data.rounds) {
-        roundResults.value = data.rounds.map((r: any) => {
+        roundResults.value = data.rounds.map((r: { roundNumber: number; winnerId: string | null }) => {
           return { round: r.roundNumber, won: r.winnerId === myBotId.value, hpA: 0, hpB: 0 }
         })
         myHp.value = amSideA.value ? data.botAHp : data.botBHp