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/fnv/fnv.ww

@@ -1,5 +1,3 @@
-// hash/fnv — FNV-1a 64-bit. Pure ww. No dependencies.
-
 package fnv;
 
 def OFFSET: u64 = 14695981039346656037;