toolchain: banner purge + WHY-only comment sweep (rule 8)

selfhost/, cmd/, internal/ join the tree-wide sweep: every section
banner dies (91 selfhost + the cmd C-style dividers -> 0); narration
and stale contracts deleted (pre-#22 bundler notes, retired
single-PT_LOAD and no-archive claims, superseded ABI tables); every
ref/harec/qbe cite, task cite, encoding/ELF contract, and rule-10
twin pointer kept; lost lifetime/rationale lines restored where the
sweep over-cut (elf_globals ownership, kwtab linear-scan). Comment-
only proven: all five wwstage tool binaries byte-identical across
the sweep; test-commit, test-byteid (161+1399, 0 pinned-divergent),
and test-bootstrap (fixed point + 991-995 byte-id) all exit 0.
The read-through banked 66 latent-bug leads (checkpoint).

selfhost/cmd/wcc/cgenstmt.ww

@@ -1,21 +1,9 @@
-// selfhost/cmd/wcc/cgenstmt.ww — split out of cgen.ww.
-//
-// cgstmt is a thin dispatcher over n.kind; each branch defers to a
-// per-kind helper: cgblock, cgreturn, cgexprstmt, cglet, cgif, cgfor,
-// cgmassign, cgbreak, cgcontinue.
-//
-// The expression generator (cgexpr) lives in cgenexpr.ww; the
-// foundation (types, emit primitives, collect* tables, FFI/module
-// maps) lives in cgen.ww.
-
 package wcc;
 
 import os;
 import syntax;
 import strconv;
 
-// ---- statement cgen --------------------------------------------------
-
 fn cgstmt(c: *cgen, n: *syntax.node) void = {
 	if (n == nil) { return; };
 	let k: syntax.nkind = n.kind;
@@ -64,9 +52,8 @@ fn cgstmt(c: *cgen, n: *syntax.node) void = {
 };
 
 fn cgyield(c: *cgen, n: *syntax.node) void = {
-	// Evaluate the value into AX (and BX for str), then JMP to the
-	// enclosing match's end label. Falls through silently if there
-	// is no active match — should be a checker error eventually.
+	// Falls through silently if there is no active match — should be
+	// a checker error eventually.
 	if (n.lhs != nil) { cgexpr(c, n.lhs); };
 	if (c.yieldtop > 0) {
 		let tgt: str = c.yieldbuf[c.yieldtop - 1];
@@ -100,8 +87,6 @@ fn cgblock(c: *cgen, n: *syntax.node) void = {
 	return;
 };
 
-// rundefers — emit cgexpr for every queued defer in LIFO order.
-// Called from cgreturn and the cgfn implicit-return path.
 fn rundefers(c: *cgen) void = {
 	let i: i32 = c.defertop - 1;
 	for (i >= 0) {
@@ -3178,11 +3163,6 @@ fn cgfor(c: *cgen, n: *syntax.node) void = {
 	return;
 };
 
-// Tuple-destructure assign: `a, b = call();`. The call's tuple
-// return lands in (AX, DX); push DX to free it, store AX into
-// the first lvalue, then pop DX into the second. Mirrors
-// cmd/w6c/cgen.c:2424-2440. Lvalues beyond two are dropped (same
-// as C — no fixture uses >2 today).
 fn cgmassign(c: *cgen, n: *syntax.node) void = {
 	// #83: positional per-element destructure REASSIGN. Same cursor as
 	// cgmlet (and cgreturn; harec create_unpack_bindings,
@@ -3394,17 +3374,6 @@ fn cgmassign(c: *cgen, n: *syntax.node) void = {
 	return;
 };
 
-// Multi-let from a tuple-returning call: `let n, s = call();` or
-// `let (n, s) = call();`. wwstage has no checker, so each binding's
-// type is taken from its explicit annotation (l.lhs) when present
-// or inferred from the called fn's return-type tuple element.
-//
-// Per the AX:DX:CX:R8 return convention (mirrors C cgen nkind.N_MLET):
-//   (scalar, scalar) — AX → l0, DX → l1.
-//   (scalar, str)    — AX → scalar slot, (DX, CX, R8) → str slot
-//                      as (.ptr, .len, .cap). Position-agnostic — the
-//                      regs are routed by element type, not by AX/DX.
-//                      str IS []u8 (24B): cap rides R8 (#1/Phase 3, task #5).
 fn cgmlet(c: *cgen, n: *syntax.node) void = {
 	let rhs: *syntax.node = n.rhs;
 	if (rhs == nil) { return; };
@@ -3958,7 +3927,6 @@ fn cgforrange(c: *cgen, n: *syntax.node) void = {
 		nbinds = 1;
 	};
 
-	// init: ioff(BP) = 0
 	emitline("\tMOVQ\t$0, ");
 	emitoff(ioff: i64);
 	emitline("(BP)\n");
@@ -4290,5 +4258,3 @@ fn cgcontinue(c: *cgen, n: *syntax.node) void = {
 	c.lastwasreturn = 0;
 	return;
 };
-
-