Extracts CODE_LIGATURE_CLASS and CODE_LIGATURE_DESCENDANT_CLASS into
packages/ui/lib/code-style.ts. Non-markdown CLI command surfaces
(onboarding/cli-install-instructions, runtimes/connect-remote-dialog)
can now import the class strings without pulling in the shiki +
react-markdown + katex dependency graph via the markdown barrel.
CodeBlock and Markdown continue to consume the constants from the
new module; the markdown barrel no longer re-exports CODE_LIGATURE_CLASS.
MUL-2793
Co-authored-by: J <j@multica.ai>
Co-authored-by: multica-agent <github@multica.ai>
