1. Rename goto_engineering_post_page/2 to visit_engineering_path/2 for
better accuracy (used for both post pages and tag pages)
2. Simplify Makefile test target by removing explicit ecto.create and
ecto.migrate commands (mix test handles migrations automatically)
3. Update blog_test.exs header comment to reflect actual changes made
4. Move Sandbox alias to top level in data_case.ex