feat: add configuration and default image for blog posts

- Introduced a new configuration file to centralize author information and default image settings for blog posts.
- Added a default image path in the blog post configuration for improved content presentation.
- Updated blog post schema to utilize the new configuration for author details, enhancing structured data representation.

src/config.ts

@@ -0,0 +1,10 @@
+export const config = {
+	author: {
+		name: "Valentin Popov",
+		url: "https://popov.link/",
+		sameAs: ["https://www.linkedin.com/in/valentineus/", "https://github.com/valentineus"],
+	},
+	posts: {
+		defaultImage: "/images/photo.png",
+	},
+};