White-box @tests move into a colocated 'package regex' file (Hare
+test.ha analogue; #6 non-T drop plays the build-tag role), black-box
@tests stay in package regex_test — Go's foo/foo_test split. The
wb/ stub driver is documented-temporary scaffolding: a same-dir
importer file-resolves to regex.ww before dir-enumeration, so only a
different-dir import bundles the whitebox sibling (task #33 retires
it). CLAUDE.md rule-9 carve-out updated (#5 closed, gate was #6).
