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single-PT_LOAD and no-archive claims, superseded ABI tables); every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).

cmd/wcc/tok.c

@@ -1,10 +1,3 @@
-/*
- * tok.c — token names, keyword lookup, debug printer.
- *
- * One table-of-records keyed by kind. The keyword subset is also
- * scanned linearly during lexing — fewer than 25 entries, a hash
- * isn't worth it.
- */
 #include "ww.h"
 #include <string.h>
 
@@ -13,7 +6,8 @@ struct kwent {
 	Tkind	kind;
 };
 
-/* keep alphabetised, so kwlookup is easy to read. */
+/* keep alphabetised, so kwlookup is easy to read. Scanned linearly:
+ * fewer than 25 entries, a hash isn't worth it. */
 static const struct kwent kwtab[] = {
 	{ "as",       TK_AS       },
 	{ "break",    TK_BREAK    },