feat: add og:image for social media preview

<!-- 👋 Hi, thanks for sending a PR to LearningTypescript! 💖. Please fill out all fields below and make sure each item is true and [x] checked. Otherwise we may not be able to review your PR. --> ## PR Checklist - [X] Addresses an existing open issue: fixes #130 - [X] That issue was marked as [accepting prs](https://github.com/LearningTypeScript/site/issues?q=is%3Aopen+is%3Aissue+label%3A%22accepting+prs%22) - [X] Steps in [CONTRIBUTING.md](https://github.com/LearningTypeScript/site/blob/main/.github/CONTRIBUTING.md) were taken ## Overview Added the `og:image` meta tag to enhance social media sharing on platforms like Facebook. A link to Facebook's Open Graph Object Debugger for validation: [Sharing Debugger](https://developers.facebook.com/tools/debug/?q=https%3A%2F%2Fwww.learningtypescript.com) Closes #130