fix: add fallback defaults to Settings and fix limiter import in auth router

fix: resolution of critical blockers (P0/P1/P2 fixes) - async Redis, atomic credit updates, schema compatibility, task event loop safety, rate limits, timezone datetimes

fix: production readiness, security, performance, and worker refactoring

diagnose: add debug-worker endpoint to track background worker thread status

fix: use SimpleWorker to prevent os.fork crashes in background thread

fix: implement custom ThreadSafeDeathPenalty class for RQ worker thread

fix: update LLM model names to active NVIDIA catalog and add worker thread signal fixes

fix: patch _install_signal_handlers on RQ worker to run inside background thread

fix: set handle_signals=False to allow RQ worker to run inside background daemon thread

fix: run background worker on app startup to process enqueued jobs

Restore standard CORSMiddleware with credentials and Vercel preview domain regex matcher

Configure custom CORS middleware to handle origin header dynamically for credential-enabled requests

Initialize Archvise API backend for Hugging Face Spaces