Install Tailwind CSS v4 + shadcn/ui with Radix UI primitives. Migrate all
UI components (Sidebar, NoteList, Editor tabs, Inspector, dialogs, palette)
from BEM CSS to Tailwind utility classes and shadcn components (Button,
Input, Dialog, Badge, etc.). Map theme system to shadcn CSS variables while
preserving BlockNote editor styles untouched. Remove 8 old CSS files.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
