🐛 Fix issues with UTC time handling

- Using `.setUTCHours` can cause the day to shift at specific times

src/store.js

@@ -1,5 +1,5 @@
 import { ref, watch, computed } from "vue";
-import { getNextAndPrevDay } from "@/util";
+import { getNextAndPrevDay, setUTCMidnight } from "@/util";
 import i18n from "@/i18n";
 
 /* Router */
@@ -32,7 +32,7 @@ watch(theme, (newValue) => {
 });
 
 /* Date selector */
-export const selectedDate = ref(new Date(new Date().setUTCHours(0, 0, 0, 0)));
+export const selectedDate = ref(setUTCMidnight(new Date()));
 export const selectedDay = computed(() => selectedDate.value.getDay() - 1);
 // Jump to next Monday if it is weekend
 if (selectedDay.value == 5)