feat: distributed rendering with Celery

- celery_app.py: Celery configuration with Redis broker
- tasks.py: render_effect task with full provenance tracking
- render.py: CLI for submitting render jobs
- Successfully renders cat → dog with provenance chain

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

check_redis.py

@@ -0,0 +1,12 @@
+#!/usr/bin/env python3
+"""Check Redis connectivity."""
+
+import redis
+
+try:
+    r = redis.Redis(host='localhost', port=6379, db=0)
+    r.ping()
+    print("Redis: OK")
+except redis.ConnectionError:
+    print("Redis: Not running")
+    print("Start with: sudo systemctl start redis-server")