feat: Add PostsController and configure routes

- Added a new file `PostsController.php` in the `app/Http/Controllers` directory.
- Implemented the `index()` method to retrieve all posts using the Sheets facade.
- Implemented the `show()` method to display a single post using route model binding with Sheets.
- Updated the `RouteServiceProvider.php` file to bind the 'post' route parameter to retrieve posts from the Sheets collection.
- Created a new configuration file `sheets.php` in the `config` directory, defining default settings for collections and their corresponding sheet classes, path parsers, content parsers, and extensions.
- Added a new markdown file `hello-world.md` in the `content/posts` directory as an example post.
- Created two new blade view files: `index.blade.php` and `show.blade.php`, under the `resources/views/posts` directory, for displaying lists of posts and individual post details respectively.
- Modified the existing web routes (`web.php`) to include routes for accessing posts.

The changes enable users to view all posts on `/posts`, as well as access individual post details at `/post/{post}`.

config/filesystems.php

@@ -56,6 +56,11 @@ return [
             'throw' => false,
         ],
 
+        'posts' => [
+            'driver' => 'local',
+            'root' => base_path('content/posts'),
+        ]
+
     ],
 
     /*