Refactor code saving data

Move the code dealing with saving and loading data to server/database to
gather it all up into one place.

server/api/schedule.ts

@@ -1,6 +1,5 @@
-import { readFile } from "node:fs/promises";
-import { Schedule } from "~/shared/types/schedule";
+import { readSchedule } from "~/server/database";
 
 export default defineEventHandler(async (event) => {
-	return JSON.parse(await readFile("schedule.json", "utf-8")) as Schedule;
+	return await readSchedule();
 })