fix: use mkdocs.unified.yml for reference build (restore dark theme, nav)

Made-with: Cursor

Author: NAOR YUVAL

.github/workflows/deploy.yml

@@ -52,7 +52,7 @@ jobs:
       - name: Build reference
         run: |
           cd mpcp-reference
-          mkdocs build --config-file mkdocs.yml --strict
+          mkdocs build --config-file mkdocs.unified.yml --strict
           mv site ../_site_reference
 
       - name: Assemble site