feat: add RSS feed generation and update package metadata

- Implemented a new RSS feed generation feature in src/pages/feed.xml.ts, allowing users to follow blog updates.
- Updated package.json and package-lock.json to include license information and new type definitions for markdown-it and sanitize-html.
- Refactored createOgImage function to return Uint8Array instead of Buffer for better compatibility.
- Simplified pageSchema by removing the optional mainEntityId parameter for cleaner schema generation.

src/utils/createOgImage.ts

@@ -5,7 +5,7 @@ import { Resvg } from "@resvg/resvg-js";
 import dayjs from "dayjs";
 import satori from "satori";
 
-export async function createOgImage(title: string, datePublished: Date): Promise<Buffer> {
+export async function createOgImage(title: string, datePublished: Date): Promise<Uint8Array> {
 	const formattedDate = dayjs(datePublished).format("MMMM DD, YYYY");
 
 	const markup = await satori(