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/crc64/crc64.ww

@@ -1,5 +1,3 @@
-// hash/crc64 — CRC-64 checksum. Pure ww.
-//
 // Same shape as lib/hash/crc32: per-byte inline polynomial shift, no
 // precomputed table. Slower than Hare's table-driven path by ~8x per
 // byte but produces identical answers for the documented polynomials.
@@ -11,9 +9,7 @@ package crc64;
 def ECMA: u64 = 0xC96C5795D7870F42u64;	// ECMA-182, xz-utils
 def ISO:  u64 = 0xD800000000000000u64;	// ISO 3309 HDLC
 
-// sum64 — fold `buf` under `poly` (reversed form). Initial cval is
-// ~0u64; per byte we mix in the low byte via 8 polynomial shifts and
-// XOR with the high seven bytes shifted down.
+// sum64 — fold `buf` under `poly` (reversed form). Initial cval is ~0u64.
 export fn sum64(buf: []u8, poly: u64) u64 = {
 	let c: u64 = 0xFFFFFFFFFFFFFFFFu64;
 	let i: i32 = 0;