feat: implement Open Graph image generation and enhance configuration

- Added ogImages integration to generate Open Graph images for blog posts.
- Updated configuration to include Open Graph settings and default preview image.
- Refactored Head component to utilize new preview property for Open Graph meta tags.
- Enhanced blog post schema to include preview image for structured data representation.
- Introduced utility functions for creating Open Graph images with dynamic content.

src/integrations/ogImages.ts

@@ -0,0 +1,47 @@
+import type { AstroIntegration } from "astro";
+import { createOgImage } from "../utils/createOgImage";
+import { globby } from "globby";
+import fs from "fs/promises";
+import matter from "gray-matter";
+import path from "path";
+
+const postsDir = path.resolve("./src/content/blog");
+const outDir = path.resolve("./public/images/preview");
+
+export default function ogImageGenerator(): AstroIntegration {
+	return {
+		name: "og-images",
+		hooks: {
+			"astro:build:setup": async ({ logger }) => {
+				await fs.mkdir(outDir, { recursive: true });
+				const mdFiles = await globby("*.md", { cwd: postsDir });
+				logger.info(`${mdFiles.length} posts found`);
+
+				const results = await Promise.allSettled(
+					mdFiles.map(async (file) => {
+						const slug = file.replace(/\.md$/, "");
+						const content = await fs.readFile(path.join(postsDir, file), "utf-8");
+						const { data } = matter(content);
+
+						const png = await createOgImage(data.title, data.datePublished);
+						const outPath = path.join(outDir, `${slug}.png`);
+						await fs.writeFile(outPath, png);
+
+						logger.info(`OG image created: ${slug}`);
+					})
+				);
+
+				results.forEach((r) => {
+					if (r.status === "rejected") {
+						logger.error(`Error for ${r.reason.slug}: ${r.reason.message}`);
+					}
+				});
+
+				const failures = results.filter((r) => r.status === "rejected");
+				if (failures.length) {
+					throw new Error(`Failed to generate OG images for ${failures.length} posts`);
+				}
+			},
+		},
+	};
+}