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/ui/Select.tsx

@@ -0,0 +1,33 @@
+interface SelectOption {
+  value: string
+  label: string
+}
+
+interface SelectProps {
+  value: string
+  onChange: (value: string) => void
+  options: SelectOption[]
+  placeholder?: string
+  className?: string
+}
+
+export function Select({ value, onChange, options, placeholder, className = '' }: SelectProps) {
+  return (
+    <select
+      value={value}
+      onChange={e => onChange(e.target.value)}
+      className={`input ${className}`}
+    >
+      {placeholder && (
+        <option value="" disabled>
+          {placeholder}
+        </option>
+      )}
+      {options.map(opt => (
+        <option key={opt.value} value={opt.value}>
+          {opt.label}
+        </option>
+      ))}
+    </select>
+  )
+}