Weekly planner: Light + dark mode

What's new

Automatic dark mode: The planner now follows your active Trilium theme. Switch Trilium to a dark theme, and the planner's surfaces, text, and borders adapt automatically.

All existing #wp_* color overrides still work and now cover the neutral colors too (#wp_bg_root, #wp_color_text, #wp_border and more. See the readme file for a full list.

This is not yet available for the knowledge-debt dashboard.