feat(markdown): integrate Markdown component for enhanced text rendering

- Added a reusable Markdown component to render markdown content with styled typography for dark mode.
- Updated KanbanCard to utilize the new Markdown component for displaying feature summaries, improving readability and presentation.
- Included the `react-markdown` library as a dependency for markdown parsing.

Modified: package.json, package-lock.json, markdown.tsx, kanban-card.tsx

app/package.json

@@ -34,6 +34,7 @@
     "next": "16.0.7",
     "react": "19.2.0",
     "react-dom": "19.2.0",
+    "react-markdown": "^10.1.0",
     "sonner": "^2.0.7",
     "tailwind-merge": "^3.4.0",
     "zustand": "^5.0.9"