improve timezone discovery

frontend/src/api/client.ts

@@ -5,6 +5,7 @@ export interface ParticipantAPI {
   id: string;
   name: string;
   email: string;
+  timezone: string;
   ics_url: string | null;
   created_at: string;
   updated_at: string;
@@ -13,6 +14,7 @@ export interface ParticipantAPI {
 export interface TimeSlotAPI {
   day: string;
   hour: number;
+  start_time: string;
   availability: 'full' | 'partial' | 'none';
   availableParticipants: string[];
 }
@@ -20,6 +22,12 @@ export interface TimeSlotAPI {
 export interface CreateParticipantRequest {
   name: string;
   email: string;
+  timezone: string;
+  ics_url?: string;
+}
+
+export interface UpdateParticipantRequest {
+  timezone?: string;
   ics_url?: string;
 }
 
@@ -45,6 +53,15 @@ export async function createParticipant(data: CreateParticipantRequest): Promise
   return handleResponse<ParticipantAPI>(response);
 }
 
+export async function updateParticipant(id: string, data: UpdateParticipantRequest): Promise<ParticipantAPI> {
+  const response = await fetch(`${API_URL}/api/participants/${id}`, {
+    method: 'PATCH',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify(data),
+  });
+  return handleResponse<ParticipantAPI>(response);
+}
+
 export async function deleteParticipant(id: string): Promise<void> {
   const response = await fetch(`${API_URL}/api/participants/${id}`, {
     method: 'DELETE',