Implement rejection bulletproofing

Created atomic rejection edge function process-selective-rejection and RPC, updated moderation client to use it, and ensured resilience; added CORS wrapper. Reminder: generate package-lock.json by running npm install.

src/integrations/supabase/types.ts

@@ -6355,6 +6355,16 @@ export type Database = {
         }
         Returns: Json
       }
+      process_rejection_transaction: {
+        Args: {
+          p_item_ids: string[]
+          p_moderator_id: string
+          p_rejection_reason: string
+          p_request_id?: string
+          p_submission_id: string
+        }
+        Returns: Json
+      }
       release_expired_locks: { Args: never; Returns: number }
       release_submission_lock: {
         Args: { moderator_id: string; submission_id: string }