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>

studio/src/stores/posts.ts

@@ -1,41 +0,0 @@
-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')
-  }
-)