chore: replace dayjs with moment as date library

Moment.js provides more extensive date manipulation features compared to dayjs, which better suits our current requirements for complex date handling.

src/plugin/datetime/index.ts

@@ -1,23 +0,0 @@
-import dayjs from "dayjs"
-import duration from "dayjs/plugin/duration"
-
-dayjs.extend(duration)
-
-/**
- * Dayjs with `Duration` plugin.
- */
-export default dayjs
-
-/**
- * Formats a given datetime string into a standardised "YYYY-MM-DD HH:mm:ss" format.
- *
- * This function utilises the [dayjs](https://day.js.org/) library for parsing and formatting.
- *
- * @param {string} datetime the datetime string to format
- * @returns {string} the formatted datetime string in `YYYY-MM-DD HH:mm:ss` format
- */
-function formatDatetime (datetime: string): string {
-  return dayjs(datetime).format("YYYY-MM-DD HH:mm:ss")
-}
-
-export { formatDatetime }