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/object/archive_test.ww

@@ -70,8 +70,6 @@ fn compile(td: str, stem: str, body: str) void = {
 	};
 };
 
-// ---- selectivity (610) -------------------------------------------------
-
 @test fn selectivity() void = {
 	let td: str = testenv.fresh();
 	compile(td, "lib_good", strings.concat("package main;\n",
@@ -112,8 +110,6 @@ fn compile(td: str, stem: str, body: str) void = {
 	testenv.clean(td);
 };
 
-// ---- manyflags (632) ---------------------------------------------------
-
 fn linkwith(td: str, lnk: str, n: i32) void = {
 	let tag: str = strings.concat(lnk, "_", dec(n));
 	let exe: str = strings.concat(td, "/x_", tag);