catviz 0.1.0

Initial release

• cat_spec(): Build a Causal Assignment Tree specification from panel data
• cat_label(): Attach cohort letters and canonical labels to a spec
• cat_plot_tree(): Unified plot dispatcher — automatically selects DiD, CSDiD, or DDD tree
• cat_plot_did(): Publication-quality 2×2 DiD tree
• cat_plot_csdid(): Publication-quality CSDiD tree (Callaway–Sant’Anna staggered adoption)
• cat_plot_ddd(): Publication-quality DDD/DR-DDD tree with subgroup split
• cat_counts(): Count units or observations per CAT node
• cat_balance_table() / cat_balance_plot(): Covariate balance across nodes
• cat_diag(): Pretrend diagnostic plots (DR-DDD and CSDiD)
• cat_att_equation(): Returns the ATT formula implied by the tree
• cat_save_png(): Save a CAT plot to a high-resolution PNG
• Grayscale option (grayscale = TRUE) for black-and-white publications