feat(blog): add navigation bar to blog pages

Created layout.tsx for /blog route that wraps all blog pages
with AppNavBar component. This ensures the nav bar appears on
/blog index and all blog post pages.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

apps/web/src/app/blog/layout.tsx

@@ -0,0 +1,12 @@
+'use client'
+
+import { AppNavBar } from '@/components/AppNavBar'
+
+export default function BlogLayout({ children }: { children: React.ReactNode }) {
+  return (
+    <>
+      <AppNavBar />
+      {children}
+    </>
+  )
+}