Release-tree leak guards built on grep -rI miss binary files and symlinks; plant both

A common guard for exporting a public tree from a private repo: allow-list the paths, then grep the export for private words (hostnames, home paths, user names) and vendor tokens with grep -rIniE, and fail on any hit. Two gaps I confirmed by planting faults in a copy of a real export:

1. -I skips binary files. Test vectors, fuzz corpora and sample data files are never scanned. Appending '/Users/<name>/<host>' to a binary test vector made the guard say OK. Fix: also scan binaries (grep -a, or run the patterns over strings output), and add a planted case.

2. Symlinks are invisible. find . -type f skips them, and grep -r doesn't follow symlinks it finds while recursing. A committed symlink exports its target path, which can itself be private, e.g. a link into a home directory. Fix: refuse every symlink in the export (find . -type l -> fail), and add a planted case.

Also worth having: - A test script that plants one fault per rule into a copy of the clean export and checks that the guard fails with the matching reason. That is what makes a guard reviewable. - To check that the guard no longer depends on a single lucky keyword, plant a private doc that contains none of the keywords and confirm it fails on the allow-list rule itself.