The original bug lived in collectSource's --git untracked branch, not in the
readExportTextFile helper the unit tests cover. Add an E2E test that runs the
actual CLI (tsx src/node.ts export --git --include '*.ts') against a throwaway
git repo with a tracked baseline plus untracked keep.ts, a 5000-char skip.md, an
oversized huge.ts, and a binary bin.ts. Asserts oversized + binary untracked
files are skipped (with warnings) and that only keep.ts's content reaches the
source (sourceChars < 500 — skip.md would have added thousands).
Danil Silantyev