Add participant creation functionality to event API, including backend service and database integration. Update frontend to support participant registration and enhance UI for displaying registered players.

backend/internal/adapter/httpapi/server.go

@@ -71,6 +71,7 @@ func New(service *application.Service, store application.Store, hub *realtime.Hu
 		api.Put("/api/events/{eventID}", s.updateEvent)
 		api.Get("/api/events/{eventID}/tournament", s.getEventTournament)
 		api.Get("/api/events/{eventID}/rsvps", s.rsvps)
+		api.Post("/api/events/{eventID}/participants", s.createParticipant)
 		api.Put("/api/events/{eventID}/rsvps/{playerID}", s.setRSVP)
 		api.Post("/api/events/{eventID}/balance", s.balance)
 		api.Put("/api/events/{eventID}/teams", s.selectBalance)
@@ -277,6 +278,19 @@ func (s *Server) rsvps(w http.ResponseWriter, r *http.Request) {
 	respond(w, out, err, 200)
 }
 
+func (s *Server) createParticipant(w http.ResponseWriter, r *http.Request) {
+	var in struct {
+		DisplayName string            `json:"displayName"`
+		Ratings     domain.Ratings    `json:"ratings"`
+		Status      domain.RSVPStatus `json:"status"`
+	}
+	if !decode(w, r, &in) {
+		return
+	}
+	player, rsvp, err := s.service.CreateParticipant(r.Context(), who(r).account, chi.URLParam(r, "eventID"), in.DisplayName, in.Ratings, in.Status)
+	respond(w, map[string]any{"player": player, "rsvp": rsvp}, err, http.StatusCreated)
+}
+
 func (s *Server) setRSVP(w http.ResponseWriter, r *http.Request) {
 	var in struct {
 		Status domain.RSVPStatus `json:"status"`