test: re-cite retired-mechanism comments in surviving carriers

The migrate-and-retire audit left the surviving carriers as the only
files still describing the retired combined.ww amalgamator as live:
m2wwi/m3sep headers claimed .wwi was dead code, four byteid carriers
carried dead cleanup of never-written .combined.ww intermediates, and
sepbuild's enumeration mirror plus lib_byteid's completeness scan
still skipped the retired artifact form (the same silent
accommodation just removed from both drivers — dropping it here
surfaced and flushed 39 stale untracked amalgamator outputs across
lib/, which the gates now reject loudly). Remaining mentions are
past-tense history or quoted diagnostics.

test/wcc/784_xmod_alias_struct_collide_run.c

@@ -45,7 +45,7 @@
  * The dispatcher uses a BRANCHED callee (void arm → -1, fn-ptr arm →
  * v+100) so the field load actually feeds control flow (gate-blind
  * discipline). cstage `ww build` + run pins runtime; raw w6c vs w6c_ww
- * `.s` cmp on the driver-produced combined.ww pins rule-10 byte-id
+ * `.s` cmp on the self-built two-module unit pins rule-10 byte-id
  * (the discriminating net for #223 — pre-fix the dispatcher diverges
  * `MOVQ reader(SB)` vs the pointer-field load).
  *