refactor(clean): drop clean_dev_editors; clean_code_editors is the live one

clean_developer_tools dispatches to clean_code_editors (lib/clean/app_caches.sh),
not the orphan clean_dev_editors that lived in lib/clean/dev.sh. The orphan
had 29 lines of VS Code/Cursor/Zed cache logic plus two bats tests but zero
production callers. Dropping both.