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/hash/adler32/adler32.ww

@@ -1,4 +1,4 @@
-// hash/adler32 — Adler-32 checksum (RFC 1950). Pure ww.
+// Adler-32 checksum (RFC 1950).
 //
 // Hare ships a hash::hash-shaped streaming type backed by io::stream;
 // we ship the pure-buffer subset here, same shape as lib/hash/fnv.