#74 exported a function from a .css.ts file. vitest's plugin tolerates it, vite build's compile does not
("Invalid exports"), so dev did not build. The helper and its custom-property name move to skyLabelInk.ts;
a test compiles the three .css.ts files that use it the build's way and fails on the old arrangement.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>