fix: clean up theme.R and logo.R before restyling

theme.R:
- Remove deprecated legend.text.align and legend.title.align (ggplot2 3.5.0)
- Remove stale @importFrom graphics plot (unused in theme function)

logo.R:
- Fix make_logo_grob() spurious two-row data frame (drop aes/data from canvas)
- Fix add_logo_ga() caption measurement always using first plot; now uses max
  across all plots with captions
- Fix add_logo_ga() ncol hardcoded to 2; now uses length(plot_list)
- Fix add_logo_ga() widths silently ignored in nrow > 1 path; now warns
- Replace deprecated qplot() in examples with ggplot() equivalents
- Fix native = T -> TRUE in plot_jpeg()

NAMESPACE

@@ -41,7 +41,6 @@ export(z_gap_test)
 export(z_univariate)
 import(ggplot2)
 importFrom(ggplot2,theme)
-importFrom(graphics,plot)
 importFrom(graphics,rasterImage)
 importFrom(grid,grid.draw)
 importFrom(grid,rasterGrob)