rashnu 0.1.0

New features

• Initial release of rashnu package.
• Includes interactive Shiny app rashnuBasic() for sample size calculation.
• Supports:
  • Two-group non-inferiority trials
  • Two-group superiority trials (Lakatos method)
  • One-sample survival test (transformation-based)

Internal improvements

• Added unit tests using testthat.
• Ensured all code is ASCII-compliant and CRAN-ready.