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/log/silent_test.ww

@@ -23,9 +23,7 @@ import memio;
 	assert(!(mem.pos != 0));
 };
 
-// The silent logger's printfln callback discards args without touching
-// fmt or any sink. Same pattern as [[silentwritesnothing]] for the
-// bare-args path.
+// Same pattern as [[silentwritesnothing]] for the bare-args path.
 @test fn silentignoresprintfln() void = {
 	let buf: [16]u8;
 	let mem = memio.fixed(buf[0:16]);