Replace the monolithic 1268-line .vimrc with a thin loader that sources
12 modules under modules/ (env, plugins, core, ui, editing, navigation,
lsp, lint, git, writing, languages, tools). Each module is independently
readable and can be toggled by commenting one line.
Add interactive tutorial (tutor/chopsticks.tutor) with 10 lessons covering
all features. Users can run :ChopsticksLearn to start.
