Improve error handling and authentication for uploads and notifications

Refactor PhotoUpload component to fetch session token before polling, enhance error handling in NotificationService and versioningHelpers with `instanceof Error` checks, and add comprehensive validation for request body fields in the create-novu-subscriber Supabase function.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 8d708ff6-09f1-4b67-8edc-de3fcb2349b3
Replit-Commit-Checkpoint-Type: intermediate_checkpoint

supabase/functions/upload-image/index.ts

@@ -1,6 +1,9 @@
 import { serve } from "https://deno.land/std@0.168.0/http/server.ts"
 import { createClient } from 'https://esm.sh/@supabase/supabase-js@2'
 
+// TODO: In production, restrict CORS to specific domains
+// For now, allowing all origins for development flexibility
+// Example production config: 'Access-Control-Allow-Origin': 'https://yourdomain.com'
 const corsHeaders = {
   'Access-Control-Allow-Origin': '*',
   'Access-Control-Allow-Headers': 'authorization, x-client-info, apikey, content-type',