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

Every // ---- section banner dies (132 -> 0): names carry the WHAT.
Narration deleted (filename restatements, run-with lines, what-the-
next-line-does); every ref/hare cite, task cite, divergence, ABI/
layout contract, and ownership qualifier kept (borrowed-view lines
restored where the sweep over-cut). Comment-only proven: all 442
walk-workdir .s and 32 import-probe .s byte-identical before/after;
libbyteid 56-roster all-ID.

lib/strings/iter_test.ww

@@ -131,7 +131,6 @@ import encoding.utf8;
 	};
 };
 
-// ---- prev / riter / iterstr / slice / position -----------------------
 // ref/hare/strings/iter.ha:84-127. The Hare @test fn iter body uses
 // `s = riter(...)` mid-test to swap the iterator's direction; ww's
 // sret-into-existing-slot path handles that fine (probed pre-port).
@@ -302,4 +301,3 @@ import encoding.utf8;
 	match (strings.next(&rit)) { case let r: rune => void; case utf8.done => { abort(); }; };
 	assert(!(!streq(strings.iterstr(&rit), "he")));
 };
-