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/embed.go

@@ -1,22 +0,0 @@
-//go:build !testing
-
-package studio
-
-import (
-	"embed"
-	"io/fs"
-	"net/http"
-	"path"
-)
-
-//go:embed dist/*
-var distFS embed.FS
-
-func Handler() http.Handler {
-	sub, _ := fs.Sub(distFS, "dist")
-	return http.FileServer(http.FS(sub))
-}
-
-func Read(name string) ([]byte, error) {
-	return distFS.ReadFile(path.Join("dist", name))
-}