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Improve CORS handling and error logging to fix moderation edge cases:
- Add x-idempotency-key to allowed CORS headers and expose explicit POST methods
- Extend CORS headers to include Access-Control-Allow-Methods
- Update edge function tracing and client error handling to better detect and log CORS/network issues
- Enhance error handling utilities to surface CORS-related failures and provide clearer user messages

supabase/functions/_shared/cors.ts

@@ -9,6 +9,7 @@ const STANDARD_HEADERS = [
   'x-client-info', 
   'apikey',
   'content-type',
+  'x-idempotency-key',
 ];
 
 // Tracing headers for distributed tracing and request tracking
@@ -36,6 +37,7 @@ export const corsHeaders = {
 export const corsHeadersWithTracing = {
   'Access-Control-Allow-Origin': '*',
   'Access-Control-Allow-Headers': ALL_HEADERS.join(', '),
+  'Access-Control-Allow-Methods': 'GET, POST, PUT, DELETE, PATCH, OPTIONS',
 };
 
 /**