chore(deps): Update dependencies and enhance API error handling

- Added '@vercel/analytics' to package.json for improved analytics tracking.
- Updated 'next' version from 15.0.2 to 15.0.3 to incorporate the latest features and fixes.
- Refactored API routes for invitations and studies to improve error handling and response structure.
- Enhanced permission checks in the invitations and studies API to ensure proper access control.
- Removed the participants dashboard page as part of a restructuring effort.
- Updated the database schema to include environment settings for users and studies.
- Improved the dashboard components to handle loading states and display statistics more effectively.

src/components/sidebar.tsx

@@ -23,7 +23,6 @@ import { Logo } from "~/components/logo"
 const navItems = [
   { name: "Dashboard", href: "/dashboard", icon: LayoutDashboard },
   { name: "Studies", href: "/dashboard/studies", icon: FolderIcon },
-  { name: "Participants", href: "/dashboard/participants", icon: UsersRoundIcon },
   { name: "Trials", href: "/dashboard/trials", icon: LandPlotIcon },
   { name: "Forms", href: "/dashboard/forms", icon: FileTextIcon },
   { name: "Data Analysis", href: "/dashboard/analysis", icon: BarChartIcon },