refactor: move studio to frontends workspace

- Move studio from root to frontends/studio/
- Add owner-tools frontend for live blog admin UI
- Add shared ui component library
- Set up npm workspaces for frontends
- Add enhanced code block extension for editor

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontends/studio/src/components/shared/Section.tsx

@@ -0,0 +1,21 @@
+import type { ReactNode } from 'react'
+
+interface SectionProps {
+  title: string
+  description?: string
+  children: ReactNode
+}
+
+export function Section({ title, description, children }: SectionProps) {
+  return (
+    <div className="section">
+      <div className="mb-4">
+        <h2 className="text-sm font-medium text-text">{title}</h2>
+        {description && (
+          <p className="text-xs text-muted mt-1">{description}</p>
+        )}
+      </div>
+      <div className="space-y-4">{children}</div>
+    </div>
+  )
+}