Brummel
3d9fbc68c6
DESIGN.md: removes "No parameterised ADTs" from the gap list,
adds an entry under "what is supported" that names the per-use-
site substitution scheme and the `llvm_type(Type::Var)` hard-error
defence. Smoke-test list extended with `box.ail.json` and
`maybe_int.ail.json`. Boundary snapshot moved from "end of Iter 12"
to "end of Iter 13".
JOURNAL.md: single Iter 13 entry covering 13a/b/c. Records the
hash-invariant regression test, the architect-flagged debt I
deliberately did not touch (poly-fn-as-value asymmetry, builtins
triple-source, `synth_arg_type` shortcuts on If/Match), the
KISS observation that 13b's "no mono-queue for types" was the
right call, and the process note that this was the first iter
worked strictly through `/agents/` after the role pin in 3df943d.
Plan iteration 14 queued: list_map-as-`List a` rewrite, GC/arena,
poly-fn-as-value.