Refactor quarto report

[grst]

Description of feature

The quarto report has grown quite a bit and different parts are redundant and/or inconsistent. The whole report should be refactored holistically:

• Have one data wrangling section at the top, and reuse dataframes throughout the report
• use dplyr/tidyr for all dataframe manipulations
• use plotly wherever possible
• Replace as many of the cat(paste0("### heading")) with plain markdown
• consider having a file with helper functions

Maybe the report could also be split up into independent "modules" that can be activated via params, in case someone wants to disable certain sections, see e.g. #487