Introduces src/lib/logger.ts emitting JSON lines (level, message, data)
compatible with Cloudflare Logpush. Replaces all console.log/warn/error
calls in email-processor.ts, index.ts, and hub.ts with structured logger
calls. Extracts waitUntilSafe into src/utils/worker.ts to avoid duplicating
the executionCtx guard across routes.
Co-Authored-By: Claude Sonnet 4.6 <[email protected]>
