Enhance HRIStudio with immersive experiment designer and comprehensive documentation updates

- Introduced a new immersive experiment designer using React Flow, providing a professional-grade visual flow editor for creating experiments.
- Added detailed documentation for the flow designer connections and ordering system, emphasizing its advantages and implementation details.
- Updated existing documentation to reflect the latest features and improvements, including a streamlined README and quick reference guide.
- Consolidated participant type definitions into a new file for better organization and clarity.

Features:
- Enhanced user experience with a node-based interface for experiment design.
- Comprehensive documentation supporting new features and development practices.

Breaking Changes: None - existing functionality remains intact.

src/app/(dashboard)/studies/[id]/page.tsx

@@ -252,14 +252,14 @@ export default async function StudyDetailPage({
                     >
                       <div className="flex h-8 w-8 items-center justify-center rounded-full bg-blue-100">
                         <span className="text-sm font-medium text-blue-600">
-                          {(member.user.name || member.user.email)
+                          {(member.user.name ?? member.user.email)
                             .charAt(0)
                             .toUpperCase()}
                         </span>
                       </div>
                       <div className="min-w-0 flex-1">
                         <p className="truncate text-sm font-medium text-slate-900">
-                          {member.user.name || member.user.email}
+                          {member.user.name ?? member.user.email}
                         </p>
                         <p className="text-xs text-slate-500 capitalize">
                           {member.role}