Add invite links

frontend/src/api/marathons.ts

@@ -1,5 +1,5 @@
 import client from './client'
-import type { Marathon, MarathonListItem, LeaderboardEntry, ParticipantWithUser, ParticipantRole, GameProposalMode } from '@/types'
+import type { Marathon, MarathonListItem, MarathonPublicInfo, LeaderboardEntry, ParticipantWithUser, ParticipantRole, GameProposalMode } from '@/types'
 
 export interface CreateMarathonData {
   title: string
@@ -21,6 +21,12 @@ export const marathonsApi = {
     return response.data
   },
 
+  getByCode: async (inviteCode: string): Promise<MarathonPublicInfo> => {
+    // Public endpoint - no auth required
+    const response = await client.get<MarathonPublicInfo>(`/marathons/by-code/${inviteCode}`)
+    return response.data
+  },
+
   create: async (data: CreateMarathonData): Promise<Marathon> => {
     const response = await client.post<Marathon>('/marathons', data)
     return response.data