feat: Refactor cart storage to use API architecture

Move store_cart functionality from main EventsController to API namespace:
- Add store_cart method to Api::V1::EventsController with API key bypass
- Remove store_cart from main EventsController
- Update routes to use RESTful API endpoint structure
- Maintain session-based cart storage for frontend compatibility

app/controllers/api/v1/events_controller.rb

@@ -4,8 +4,11 @@
 module Api
   module V1
     class EventsController < ApiController
+      # Skip API key authentication for store_cart action (used by frontend forms)
+      skip_before_action :authenticate_api_key, only: [:store_cart]
+      
       # Charge l'évén avant certaines actions pour réduire les duplications
-      before_action :set_event, only: [ :show, :update, :destroy ]
+      before_action :set_event, only: [ :show, :update, :destroy, :store_cart ]
 
       # GET /api/v1/events
       # Récupère tous les événements triés par date de création (du plus récent au plus ancien)
@@ -54,6 +57,18 @@ module Api
         head :no_content
       end
 
+      # POST /api/v1/events/:id/store_cart
+      # Store cart data in session (AJAX endpoint)
+      def store_cart
+        cart_data = params[:cart] || {}
+        session[:pending_cart] = cart_data
+
+        render json: { status: "success", message: "Cart stored successfully" }
+      rescue => e
+        Rails.logger.error "Error storing cart: #{e.message}"
+        render json: { status: "error", message: "Failed to store cart" }, status: 500
+      end
+
       private
 
       # Trouve un événement par son ID ou retourne 404 Introuvable