Closes four surface-form bypass vectors against fix#2 that were
real holes: contractions ("you're now a pirate" did not match marker
"you are now"), curly quotes (U+2019 vs U+0027), em-dashes (token
splicing), and verb morphology ("becoming"/"transformed"/"dropped"
did not stem to the bare redirect-verb set).
teaching/review.py:
- _normalize() folds Unicode punctuation and expands 28 common
English contractions (you're, it's, let's, don't, won't, etc.)
before rule (a) substring matching and rule (b/c/d) tokenisation.
- _stem_verb() folds -ing / -ed / -es / -s morphology with silent-e
drop and doubled-consonant handling, so "becomes" / "becoming" /
"became"-class forms match the bare redirect-verb stem.
- Rule (d) window now uses verb stems, not raw tokens.
Verification: ten splits (v1-v5, public + holdouts) at 100% attack
rejection and 100% legitimate acceptance. v5 (32 attacks + 18
legitimates) is the new regression gate, exercising every fold class
plus legitimates that themselves use contractions ("wisdom's broader",
"knowledge isn't merely collected").
Tests: test_reviewed_teaching_loop.py 5/5, test_pipeline_teaching_integration.py
5/5, test_identity_gate.py 17/17 (including 5 TestWouldViolatePredicate
tests from prior commit).
a853cb5b3b