Add @concept tags, and generalized woolf_test

Version 0.9.0 (2026-01-17)

This is a major release of the package, adding structure to dataset examples via @concept tags and introducing an new extension Woolf's test for homogeneity of odds ratios.

• Begin to categorize the datasets in the package with @concept tags
• Begin to flesh out more general conception of CDA
• datasets(): added ndim arg; package="vcdExtra" default
• Added a tidyCat hex logo
• Generalized vcd::woolf_test() to handle strata better, with special handling for 2 x 2 x R x C case.
• Completed extension of vcd::woolf_test() to fully handle R x C strata, with tests for rows/cols/residuals
• Added GH actions R-CMD-check & pkgdown
• Now depends R (>= 4.1.0) due to use of native pipe |>
• Fixed some broken URLs in R/data.R