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/strconv/stof_test.ww

@@ -1,5 +1,3 @@
-// stoftest — exercises lib/strconv/stof.ww (Hare stof.ha port).
-//
 // Ports ref/hare/strconv/stof.ha's @test vectors (stof64 / stof32 /
 // stofhex). Comparisons are BIT-level (math.f64bits / f32bits) so a
 // sign flip (-0.0 vs 0.0) or a 1-ulp miss fails the row rather than
@@ -14,8 +12,6 @@ import strconv;
 import math;
 
 
-// ---- unwrap helpers (bit-exact value checks) -------------------------
-
 fn chk64(s: str, b: base, want: f64) bool = {
 	match (stof64(s, b)) {
 	case let v: f64 => { return math.f64bits(v) == math.f64bits(want); };
@@ -89,7 +85,6 @@ fn nan32(s: str) bool = {
 	return false;
 };
 
-// ---- stof64 ----------------------------------------------------------
 // ref/hare/strconv/stof.ha:530.
 
 @test fn stof64_dec() void = {
@@ -141,7 +136,6 @@ fn nan32(s: str) bool = {
 	assert(!(!nan64("naN")));
 };
 
-// ---- stof32 ----------------------------------------------------------
 // ref/hare/strconv/stof.ha:560.
 
 @test fn stof32_dec() void = {
@@ -180,7 +174,6 @@ fn nan32(s: str) bool = {
 	assert(!(!chk32("9.19100241453305036800e+20", base.DEC, 9.19100241453305036800e+20f32)));
 };
 
-// ---- stofhex ---------------------------------------------------------
 // ref/hare/strconv/stof.ha:590. Hex-float surface-form literals (0x1.fp-2,
 // math::F64_MAX_NORMAL, …) are spelled as IEEE-754 bit patterns since ww
 // has no hex-float literal lexer / no F*_MAX_NORMAL math consts.