Rename AcountSession to ServerSession

Start the work of clearly distingushing client side types, server side
types and types shared over the API by renaming "AccountSession" and
"Session" names used on the server to "ServerSession".

server/api/admin/delete-database.post.ts

@@ -1,7 +1,7 @@
 import { deleteDatbase, readAccounts } from "~/server/database";
 
 export default defineEventHandler(async (event) => {
-	const session = await requireAccountSession(event);
+	const session = await requireServerSession(event);
 	let accounts = await readAccounts();
 	const sessionAccount = accounts.find(
 		account => account.id === session.accountId