test(hygiene): no tracked file may carry a term from the local exclusion list — red

Sector-specific example material is to be replaced by generic, fictitious
examples; this test keeps it replaced. Every tracked file's path, text and the
text a reader gets out of a binary fixture (zip members, inflated PDF streams)
is matched against a term list kept in a git-ignored local file
(`*.local.txt`). Without the file the check is skipped with a message, never
passed; the scanner's known-positive runs on a synthetic term either way. An
empty exception list is tested as a list.

Red on af2d1d3 with the list in place: 161 of 426 tracked files, 11 file
names, 12 of 27 binary fixtures.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.gitignore

@@ -14,6 +14,7 @@ build/
 .env
 .env.*
 *.local.md
+*.local.txt
 .DS_Store
 
 # Local-only: public remote — never publish session state or internal briefs