feat(mobile): redesign menu with sidebar integration

- Move mobile nav controls to left side (hamburger, search, theme)
- Add sidebar TOC to mobile menu when page has sidebar layout
- Hide desktop sidebar on mobile since accessible via hamburger
- Standardize mobile menu typography with CSS variables
- Use font-family inherit for consistent fonts across menu elements

src/components/BlogPost.tsx

@@ -405,6 +405,14 @@ export default function BlogPost({ content }: BlogPostProps) {
               </h5>
             );
           },
+          h6({ children }) {
+            const id = generateSlug(getTextContent(children));
+            return (
+              <h6 id={id} className="blog-h6">
+                {children}
+              </h6>
+            );
+          },
           ul({ children }) {
             return <ul className="blog-ul">{children}</ul>;
           },