Fixes dark mode toggle, landing page layout, dashboard structure, and removes unused imports. Replit-Commit-Author: Agent Replit-Commit-Session-Id: d7e7c4e8-20cb-41c4-9d0e-79f48938fede Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/9777c70b-fc38-4831-8d6b-78dfffe041b0/d4eed189-5f49-4ca5-967b-42e14b879685.jpg