Refactor Phase 3 Batch 2–4 Novu-related functions to use the createEdgeFunction wrapper, replacing explicit HTTP servers with edge wrapper, adding standardized logging, tracing, and error handling across subscriber management, topic/notification, and migration/sync functions.
Consolidate CORS handling by introducing a shared supabase/functions/_shared/cors.ts and migrate edge functions to import from it. Remove inline cors.ts usage across functions, standardize headers (including traceparent and x-request-id), and prepare for environment-aware origins.
