Fix: inherit the monorepo root's DESIGN.md in detect design-system rules (#570)

findDesignRoot stopped at the first package.json boundary, so every
design-system rule silently abstained for files inside monorepo
workspaces. The walk now continues past a workspace boundary to the
monorepo root that owns it, recognized the same way context.mjs does
(declared workspace globs, or a marker file beside apps/ or packages/
children). A nested repo with its own .git, a workspace-owned
DESIGN.md, and non-monorepo projects keep their existing behavior.

Written with AI assistance (Cursor); reviewed by maintainer.

Co-authored-by: Cursor <cursoragent@cursor.com>

scripts/test-suites.mjs

@@ -107,6 +107,7 @@ export const SUITES = {
           'tests/detect-antipatterns-fixtures.test.mjs',
           'tests/detect-antipatterns-browser.test.mjs',
           'tests/detect-cli-design-contamination.test.mjs',
+          'tests/detect-cli-design-monorepo.test.mjs',
           'tests/detect-cli-stdin-dispatch.test.mjs',
         ],
       },