test: banner purge + WHY-only comment sweep (rule 8)

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.

test/wcc/992_w6l_ww.c

@@ -1,13 +1,9 @@
 /*
- * 992_w6l_ww — explicit bootstrap gate for the ww-side w6l port.
- *
- * Diffs the C-built `w6l` against the ww-built `w6l_ww` on a corpus of
- * link inputs. Both must produce byte-identical static ELF binaries.
- * The corpus mixes:
- *   - a single .o input (no archive resolution)
- *   - a .o + libwwrt.a link, exercising the SysV `ar` two-pass loader
- *
- * Any divergence is a port bug in selfhost/cmd/w6l/.
+ * Explicit bootstrap gate: the C-built `w6l` and the ww-built `w6l_ww`
+ * must produce byte-identical static ELF binaries on the same link
+ * inputs. Any divergence is a port bug in selfhost/cmd/w6l/. The
+ * corpus mixes a single-.o link (no archive resolution) with a
+ * .o + libwwrt.a link exercising the SysV `ar` two-pass loader.
  */
 #include <stdio.h>
 #include <stdlib.h>