refactor: make match-collector export its types, and consume them in frontend

frontend/pages/champion/[alias].vue

@@ -1,6 +1,8 @@
 <script setup lang="ts">
 import { ref, computed } from 'vue'
 
+import type { ChampionData } from 'match_collector'
+
 const route = useRoute()
 const championAlias = route.params.alias as string