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/xmod/label_test.ww

@@ -71,8 +71,6 @@ fn catasm(sepdir: str) str = {
 	return out;
 };
 
-// ---- fnlabel (#9 + #12) ------------------------------------------------
-
 @test fn fnlabel() void = {
 	let fixdir: str = strings.concat(testenv.repo(),
 		"/test/wcc/data/fnlabelmangle");
@@ -107,8 +105,6 @@ fn catasm(sepdir: str) str = {
 	testenv.clean(td);
 };
 
-// ---- mklabel (#13) -----------------------------------------------------
-
 fn mod1locate() str = {
 	return strings.concat(
 		"package mod1;\n",

test/xmod/m1_test.ww

@@ -82,8 +82,6 @@ fn mkdirs(td: str, dirs: []str) void = {
 	};
 };
 
-// ---- m1mangle (#22 + #32) ----------------------------------------------
-
 // dirs are '/'-joined mkdir steps, parents before children.
 fn m1row(label: str, dirs: []str, rel: str, content: str, root: str,
 	want: i32) void = {
@@ -163,8 +161,6 @@ fn m1row(label: str, dirs: []str, rel: str, content: str, root: str,
 		"export fn main() int = { return cc.val(); };\n"), 3);
 };
 
-// ---- m1usehint (#40) ---------------------------------------------------
-
 fn uselayout(td: str, apick: str, onecall: str) void = {
 	let dirs: []str = ["a", "a/math", "b", "b/math", "one", "two"];
 	mkdirs(td, dirs);

test/xmod/typecheck_test.ww

@@ -57,8 +57,6 @@ fn tmo() time.duration = {
 	return (240i64 * (time.second: i64)): time.duration;
 };
 
-// ---- -T __wwtests reservation faces ------------------------------------
-
 fn tface(label: str, src: str) void = {
 	let drvs: []str = ["ww", "ww_ww"];
 	let i: i32 = 0;
@@ -100,8 +98,6 @@ fn tface(label: str, src: str) void = {
 		"@test fn checkfoo() void = { return; };\n"));
 };
 
-// ---- cross-module call-arg collision rows ------------------------------
-
 fn io2src() str = {
 	return strings.concat(
 		"package io2;\n",
@@ -181,8 +177,6 @@ fn shapemismatchmain() str = {
 		"};\n"));
 };
 
-// ---- tagged-subset cross-module leaf-bridge rows -----------------------
-
 fn xrow(label: str, esrc: str, msrc: str, expectbuild: bool) void = {
 	let drvs: []str = ["ww", "ww_ww"];
 	let i: i32 = 0;