Every section banner dies (103 -> 0) across test/lang, the observer
suites, the C carriers, and the five comment-heavy corpus fixtures;
banner provenance (#N cites, carrier numbers, repair-cluster labels)
folded into headers or adjacent WHY comments. Narration deleted; row
provenance, ref cites, divergence pins, and layout contracts kept
(fwd-ref decl-order guards and bootstrap-gate corpus rationale
restored where the sweep over-cut). Comment-only proven: all 3742
wwbuild workdir .s byte-identical before/after; test-commit and
test-byteid (161 lang + 1399 data, 0 pinned-divergent) green.
Ports 708_param_shadow_mod, 712_redecl and 961_opaque_guards into
test/tool/rejects_test.ww on testenv, one commit because the three
carriers share the single asymmetric-polarity claim (cstage rejects,
wwstage accepts) that a both-stage //ww:error fixture cannot carry.
The neg_selfimp leg drops: test/wcc/data/r948_selfimport/case.ww owns
the identical both-frontend claim.
