Add tags / categories to portfolio

See https://github.com/lewiuberg/lewiuberg.github.io for reference.

- tags -> skills (matplotlib, plotly, aws, streamlit, heroku...)
- categories -> DS, interactive visualization, python package...

Use the reference portfolio at https://github.com/lewiuberg/lewiuberg.github.io to understand the intended tags and categories, then inspect this repository's existing portfolio structure and styling entry points. The work is done when portfolio items expose tags for skills such as matplotlib, plotly, AWS, Streamlit, and Heroku, plus categories such as DS, interactive visualization, and Python package.

Written by the indexing model from the issue text.