issue(0139): by-value self-referential type segfaults (typeSizeBytes recursion)

Discovered while testing metatype self-reference: a by-VALUE self-ref
(`payload = List`, not `*List`) infinite-loops typeSizeBytes → segfault
instead of a loud "infinite size" diagnostic. PRE-EXISTING — a hand-written
source enum `enum { node: Bad; leaf }` crashes identically, so it's a
general type-system gap (the comptime F5 by-value-rejection inherits the
fix). Filed per the IMPASSABLE rule; metatype checkpoint notes it.

current/CHECKPOINT-METATYPE.md

@@ -60,7 +60,14 @@ Pick any (independent):
   never `define()`d (hard error), use-before-define.
 
 ## Known issues
-None.
+- **issue 0139 — by-value self-reference segfaults** (`typeSizeBytes` infinite
+  recursion). A by-VALUE self-referential type (`payload = List` instead of
+  `*List`) stack-overflows instead of emitting a loud "infinite size" diagnostic.
+  PRE-EXISTING (a hand-written source enum `enum { node: Bad; leaf }` crashes
+  identically) — a general type-system gap, not specific to declare/define. Closes
+  the F5 "by-VALUE self-reference rejected" item for the comptime path once fixed.
+  Filed `issues/0139-byvalue-self-reference-segfault.md`; session stopped here per
+  the CLAUDE.md IMPASSABLE rule (do not work around / roll forward after filing).
 
 ## Log
 - **Self-reference done.** `declare(name)` + `preregisterForwardTypes` (forward