✨ Add loading spinner

src/store.js

@@ -3,6 +3,7 @@ import { ref, watch } from "vue";
 import router from "./router";
 
 export const lastRoute = ref();
+export const loading = ref(false);
 
 export const substitutionFilter = ref(
   localStorage.getItem("substitutionFilter") || "all"
@@ -66,6 +67,8 @@ export const parsedTimetable = computed(() => {
 const baseUrl = import.meta.env.VITE_API_ENDPOINT || "/api";
 
 export async function fetchData() {
+  loading.value = true;
+
   const checkResponse = await fetch(`${baseUrl}/check`);
   if (checkResponse.status != 200) router.push("/login");
 
@@ -73,6 +76,8 @@ export async function fetchData() {
   fetchTimetable();
   fetchSubstitutions();
   fetchHistory();
+
+  loading.value = false;
 }
 
 export async function fetchClassList() {