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single-PT_LOAD and no-archive claims, superseded ABI tables); every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/w6a/lex.ww

@@ -1,8 +1,4 @@
-// selfhost/cmd/w6a/lex.ww — port of cmd/w6a/lex.c.
-//
-// Character-level helpers for w6a's line-oriented parser. The parser
-// itself is in parse.ww; here we keep tokenisers for identifiers and
-// numbers so parse.ww stays focused on syntax.
+// Port of cmd/w6a/lex.c.
 
 package w6a;
 
@@ -20,10 +16,6 @@ export fn isidcont(c: i32) bool = {
 	return false;
 };
 
-// parsenum — read a leading [+-]?[0x|0X|0]?digits from p[0..n-1].
-// Returns (value, consumed). Stops at first non-digit.
-// Plain Plan 9-style: $123 / $0x1f / $-7. Decimal default; 0x prefix
-// for hex; 0 prefix for octal when followed by a digit (else just 0).
 export fn parsenum(p: *u8, n: u64) (i64, u64) = {
 	// strtoll(s, end, 0) semantics, matching the C twin cmd/w6a/lex.c:30:
 	// skip leading whitespace, optional sign, base-0 prefix detection