- A new `files` table to store metadata about uploaded files, including original name and hash.
- The `users` table is updated to reference a `pfp_file_id` from the new `files` table, removing the insecure `pfp_url` field.
- A new `/file` endpoint and handler (`handlers/file.go`) are created to serve files securely based on their ID, preventing direct file system access.
- Profile editing (`handlers/profile_edit.go` and `templates/pages/profile_edit.html`) is updated to handle file uploads instead of URL inputs.
- The chat feature (`models/chat.go` and `templates/pages/chat.html`) is updated to work with the new file ID system, ensuring avatars are displayed correctly.
Should also fix#68.