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>
Split FightPage.vue into useFightPolling (SSE, polling, reconnect)
and useHumanChallenge (timer, submission, cooldown) composables.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>