test/xmod/typecheck_test.ww replaces 989_callarg_typecheck.c and
989_tagged_subset_reject.c. Preserved: both -T __wwtests reservation
faces (both stages, diagnostic required), the shape-mismatch collision
(both stages), the cstage-only same-shape #37 pin, and both tagged
leaf-bridge xmod rows. Not ported, owned elsewhere per the audit: the
carriers' twelve ordinary call-arg rows (r989_callarg_* fixtures) and
the three w6c-vs-w6c_ww byte-id rows (test-data-byteid over
r989_tagsubset_{flatten_subset,slice_subset,nested_wrap}).
test/xmod/label_test.ww replaces 706_fnlabel_mangle.c and
750_mklabel_modscoped.c with every assertion preserved (fnlabelmangle
fixture run-112 both stages; three mklabel rows with run exits and
module-qualified label needles). Strengthened: fnlabel adds the
cs==ww sepwork .s byte-id the carrier never asserted.
test/xmod/m1_test.ww replaces 989_m1mangle_run.c and
989_m1usehint_run.c with every assertion preserved (5 tree rows +
2 usehint rows, both stages, plus the leaf_collision byte-id leg;
concat order strengthened from shell glob to byte-sorted listdir).
test/xmod/collide_test.ww replaces 989_fnptrcollide_run.c and
989_barefn_collide_run.c with every assertion preserved (build-reject
both stages; run-exit 9 + exactly-one TEXT main.run/aa.run + cs==ww).
Makefile grows the XMOD_WW_TESTS block mirroring SEP_WW_TESTS, wired
into test-compiler.
