708 pinned param + clet + self-import-skip after #19 landed; the
other 4 sites where check_module_shadow is wired (N_MLET, N_FORRANGE
single, N_FORRANGE tuple, N_MCASE) had no dedicated negative-compile
row. Worker-19's note that all 6 sites use identical call shape is
true today but unpinned by tests; a future asymmetric edit could
silently disable enforcement on one site.
Adds neg_mlet (let-tuple binder shadows), neg_forrange_single
(`for shadowmod of ...`), neg_forrange_tuple (`for (shadowmod, x)
of pairs`), neg_mcase (`case let shadowmod:`). Each errors at the
binder decl line with the canonical
"<kind> '<name>' shadows imported module '<name>'" message.
708's main now runs 8/8 (param, let, mlet, forrange_single,
forrange_tuple, mcase, pos_rename, pos_selfimp).
Hojun-Cho
ed94467a0c