Share Tailwind CSS utility layering configuration between the UI and CLI

The Canvas UI and CLI both compile Tailwind CSS with tailwindcss-in-browser, but they do not use the same compileCss() options.

The UI passes unlayeredUtilities so generated display utilities can override the System module's unlayered .hidden class. This was implemented in #3555376: Avoid unintended CSS precendence due to conflicting and unlayered "hidden" class name, but we never added it to the CLI build.

This mismatch existed before the recently landed #3588661: Make CLI builds use shared Vite infrastructure and can cause responsive display utilities such as md:block to fail to override hidden in CSS built by the CLI.

Proposed resolution

Update the UI Tailwind compiler hook and the CLI Tailwind build utility to import a shared constant. Update the CLI compileCss() call to pass { unlayeredUtilities: UNLAYERED_DISPLAY_UTILITIES }, matching the existing UI behavior, and add focused test coverage for the CLI call.

Ideally this would live in a shared package, but the CLI tool already imports things from the UI codebase, and it's outside the scope of this issue to change that.