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/stores/posts.ts

@@ -0,0 +1,41 @@
+import { atom, computed } from 'nanostores'
+import { createFetcherStore, createMutatorStore } from './fetcher'
+import type { Post } from '../types'
+
+export const $posts = createFetcherStore<Post[]>(['/api/studio/posts'])
+
+export const $search = atom('')
+export const $filterStatus = atom<'all' | 'published' | 'draft'>('all')
+
+export const $filteredPosts = computed(
+  [$posts, $search, $filterStatus],
+  (postsStore, search, status) => {
+    const posts = postsStore.data ?? []
+    return posts.filter(p => {
+      const searchLower = search.toLowerCase()
+      if (search && !p.title.toLowerCase().includes(searchLower) && !p.slug.toLowerCase().includes(searchLower)) {
+        return false
+      }
+      if (status === 'published' && p.draft) return false
+      if (status === 'draft' && !p.draft) return false
+      return true
+    })
+  }
+)
+
+export const $postCounts = computed([$posts], (postsStore) => {
+  const posts = postsStore.data ?? []
+  return {
+    all: posts.length,
+    published: posts.filter(p => !p.draft).length,
+    draft: posts.filter(p => p.draft).length,
+  }
+})
+
+export const $deletePost = createMutatorStore<string>(
+  async ({ data: slug, invalidate }) => {
+    const res = await fetch(`/api/studio/posts/${slug}`, { method: 'DELETE' })
+    if (!res.ok) throw new Error('Failed to delete post')
+    invalidate('/api/studio/posts')
+  }
+)