exoplanetdata 0.1.0

• Initial release.
• Adds two datasets sourced from NASA’s Exoplanet Archive (retrieved via the REXoplanets package):
  • planets: one row per confirmed exoplanet from the Planetary Systems Composite Parameters (pscomppars) table, with host-star parameters merged in.
  • stars: reference-level stellar host parameters (stellarhosts table) — many rows per star, one per published parameter solution.
• Column names have been simplified for classroom use and units baked into names where ambiguous. Original NASA short names are preserved in the data dictionaries shipped under inst/extdata/.