feat(docs): add label to version selector in site header (#139)

Add CSS rule to display Version: label next to the MkDocs Material version selector dropdown.

Ref #134

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: wphillipmoore

docs/site/docs/stylesheets/extra.css

@@ -0,0 +1,7 @@
+.md-version::before {
+  content: "Version:";
+  margin-right: 0.4em;
+  font-size: 0.8rem;
+  color: var(--md-primary-bg-color);
+  opacity: 0.7;
+}

docs/site/mkdocs.yml

@@ -38,6 +38,9 @@ extra:
   version:
     provider: mike
 
+extra_css:
+  - stylesheets/extra.css
+
 plugins:
   - search