I loaded your app and it looks great, all the resources load. I made a user and tried to add a post then this is what happened. Do you have a clue? Also when adding an image to the create form, the file selector does not show a file was loaded.
Solved by changing line 15 of create.blade.php from this <form action="/p/" method="post" enctype="multipart/form-data">
to this <form action="/p" method="post" enctype="multipart/form-data">