frontend: refactor of the new build viewer

extracting the logic into composables

frontend/composables/useSummonerSpellMap.ts

@@ -0,0 +1,33 @@
+/**
+ * Composable for fetching and managing summoner spell data from CDragon API
+ * Returns a reactive Map of spell ID to spell data
+ */
+export const useSummonerSpellMap = () => {
+  const { data: summonerSpellsData } = useFetch<Array<SummonerSpell>>(
+    '/api/cdragon/summoner-spells',
+    {
+      lazy: true,
+      server: false
+    }
+  )
+
+  const summonerSpellMap = ref<Map<number, SummonerSpell>>(new Map())
+
+  watch(
+    summonerSpellsData,
+    (newData) => {
+      if (Array.isArray(newData)) {
+        const map = new Map<number, SummonerSpell>()
+        for (const spell of newData) {
+          if (spell?.id) {
+            map.set(spell.id, spell)
+          }
+        }
+        summonerSpellMap.value = map
+      }
+    },
+    { immediate: true }
+  )
+
+  return { summonerSpellMap }
+}