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/encoding/base32/base32_test.ww

@@ -86,7 +86,6 @@ fn enchexvec(input: str, expect: str) void = {
 };
 
 @test fn roundtrip_all_quintets() void = {
-	// Encode then decode every 5-byte combination of a small set.
 	let raw: [5]u8;
 	raw[0] = 0x00u8;
 	raw[1] = 0x55u8;