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/types/participant.ts

@@ -0,0 +1,80 @@
+// Participant type definitions for HRIStudio
+
+export interface ParticipantDemographics {
+  age?: number;
+  gender?: string;
+  grade?: number;
+  background?: string;
+  education?: string;
+  occupation?: string;
+  experience?: string;
+  notes?: string;
+  [key: string]: string | number | boolean | undefined;
+}
+
+export interface ParticipantWithStudy {
+  id: string;
+  studyId: string;
+  participantCode: string;
+  email: string | null;
+  name: string | null;
+  demographics: ParticipantDemographics | null;
+  consentGiven: boolean;
+  consentDate: Date | null;
+  notes: string | null;
+  createdAt: Date;
+  updatedAt: Date;
+  study: {
+    id: string;
+    name: string;
+    institution: string | null;
+  } | null;
+}
+
+export interface CreateParticipantData {
+  studyId: string;
+  participantCode: string;
+  email?: string;
+  name?: string;
+  demographics?: ParticipantDemographics;
+  consentGiven?: boolean;
+  consentDate?: Date;
+  notes?: string;
+}
+
+export interface UpdateParticipantData {
+  participantCode?: string;
+  email?: string;
+  name?: string;
+  demographics?: ParticipantDemographics;
+  consentGiven?: boolean;
+  consentDate?: Date;
+  notes?: string;
+}
+
+export interface ParticipantListItem {
+  id: string;
+  studyId: string;
+  participantCode: string;
+  name: string | null;
+  consentGiven: boolean;
+  consentDate: Date | null;
+  createdAt: Date;
+  studyName: string;
+}
+
+export interface ParticipantTrialSummary {
+  id: string;
+  experimentName: string;
+  status: "scheduled" | "in_progress" | "completed" | "aborted";
+  scheduledAt: Date | null;
+  startedAt: Date | null;
+  completedAt: Date | null;
+  duration: number | null;
+}
+
+export interface ParticipantDetailData extends ParticipantWithStudy {
+  trials: ParticipantTrialSummary[];
+  upcomingTrials: ParticipantTrialSummary[];
+  completedTrials: ParticipantTrialSummary[];
+}