Compiled installs always take the non-Bun branch, which called an unimported
join and threw before any runtime-tested assertion could be witnessed. The
child command selection is now a pure, platform-aware function; a missing
sibling launcher fails with its expected path.
Mechanical reformat only. Minified transpile output is byte-identical for
21 of 22 files; witness.ts differs only in three regex flag orders
(/mi -> /im), which JavaScript canonicalizes. Source-text assertions over
lib/cso now compare whitespace-insensitively with the same tokens.