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/owner-tools/src/main.tsx

@@ -0,0 +1,39 @@
+import { createRoot } from 'react-dom/client'
+import { App } from './App'
+import reset from '@unocss/reset/tailwind.css?inline'
+import css from 'virtual:uno.css?inline'
+
+function mount() {
+  const host = document.createElement('div')
+  host.id = 'writekit-owner-tools'
+  document.body.appendChild(host)
+
+  const shadow = host.attachShadow({ mode: 'open' })
+
+  const style = document.createElement('style')
+  style.textContent = reset + css + `
+    :host {
+      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
+      line-height: 1.5;
+      -webkit-font-smoothing: antialiased;
+      -moz-osx-font-smoothing: grayscale;
+    }
+  `
+  shadow.appendChild(style)
+
+  const container = document.createElement('div')
+  container.style.cssText = `
+    position:fixed;inset:0;z-index:99999;pointer-events:none;
+    --un-bg-opacity:100%;--un-text-opacity:100%;--un-border-opacity:100%;
+    --un-ring-opacity:100%;--un-shadow-opacity:100%;
+  `.replace(/\s+/g, '')
+  shadow.appendChild(container)
+
+  createRoot(container).render(<App />)
+}
+
+if (document.readyState === 'loading') {
+  document.addEventListener('DOMContentLoaded', mount)
+} else {
+  mount()
+}