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/c/libc/libc.ww

@@ -1,10 +1,8 @@
-// lib/c/libc — minimal libc bindings. Each declaration is body-less,
-// imported from the C side at link time. The @symbol attribute pins
-// the linker name; without it, the binding name itself is used.
-//
 // These declarations cover the small surface the bootstrap wants:
 // process exit, three io syscalls, and the malloc/free pair. Higher
-// ergonomics live in sibling pure-ww packages.
+// ergonomics live in sibling pure-ww packages. Each declaration is
+// body-less, resolved from the C side at link time; @symbol pins the
+// linker name (without it the binding name itself is used).
 
 package libc;