chore: remove about page and exclude /tags/ from sitemap

- Delete unused about page
- Filter /tags/ paths from sitemap generation

Author: ppippi-dev

astro.config.mjs

@@ -9,7 +9,12 @@ import rehypeKatex from 'rehype-katex';
 // https://astro.build/config
 export default defineConfig({
 	site: 'https://ppippi.dev',
-	integrations: [mdx(), sitemap()],
+	integrations: [
+		mdx(),
+		sitemap({
+			filter: (page) => !page.includes('/tags/'),
+		}),
+	],
 	markdown: {
 		remarkPlugins: [remarkMath],
 		rehypePlugins: [rehypeKatex],