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single-PT_LOAD and no-archive claims, superseded ABI tables); every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

@@ -1,6 +1,4 @@
 /*
- * obj.c — emit a tiny ELF64 relocatable object.
- *
  * Layout (in file order):
  *    [0] ELF header
  *    [1] Section .text (program bytes)
@@ -24,7 +22,6 @@
 #include <string.h>
 #include <stdio.h>
 
-/* ELF constants */
 #define ELFMAG		"\x7f""ELF"
 #define ELFCLASS64	2
 #define ELFDATA2LSB	1
@@ -54,7 +51,6 @@
 #define R_X86_64_PLT32	4
 #define ELF64_R_INFO(s,t)	(((u64)(s) << 32) | ((u64)(t) & 0xffffffff))
 
-/* growable byte buffer */
 typedef struct Buf Buf;
 struct Buf { u8 *p; size_t n, cap; };
 
@@ -157,10 +153,9 @@ a_emit_elf(Asm *a, FILE *f)
 		bput(&sym, &z, sizeof z);
 	}
 
-	/* Build symbols (defined = global; undefined = global UND). Data
-	 * symbols carry STT_OBJECT and st_shndx=SH_DATA; everything else
-	 * keeps the legacy STT_FUNC/SH_TEXT shape so non-DATAW outputs
-	 * stay byte-identical. */
+	/* Data symbols carry STT_OBJECT and st_shndx=SH_DATA; everything
+	 * else keeps the legacy STT_FUNC/SH_TEXT shape so non-DATAW
+	 * outputs stay byte-identical. */
 	int idx = 1;
 	for (Asym *s = a->syms; s; s = s->next) {
 		Sym64 e = {0};
@@ -193,7 +188,6 @@ a_emit_elf(Asm *a, FILE *f)
 		bput(r->section == 1 ? &relad : &rela, &re, sizeof re);
 	}
 
-	/* Layout offsets in the file */
 	u64 off = sizeof(Ehdr);
 	u64 off_text = off; off += a->textlen;
 	u64 off_rela = off; off += rela.n;
@@ -202,7 +196,6 @@ a_emit_elf(Asm *a, FILE *f)
 	u64 off_sym  = off; off += sym.n;
 	u64 off_str  = off; off += str.n;
 	u64 off_shstr= off; off += shstr.n;
-	/* align to 8 */
 	while (off % 8) off++;
 	u64 off_shdr = off;
 	const int NSECT = has_data