Add PostgreSQL + IPFS backend, rename configs to recipes

- Add PostgreSQL database for cache metadata storage with schema for
  cache_items, item_types, pin_reasons, and l2_shares tables
- Add IPFS integration as durable backing store (local cache as hot storage)
- Add postgres and ipfs services to docker-compose.yml
- Update cache_manager to upload to IPFS and track CIDs
- Rename all config references to recipe throughout server.py
- Update API endpoints: /configs/* -> /recipes/*
- Update models: ConfigStatus -> RecipeStatus, ConfigRunRequest -> RecipeRunRequest
- Update UI tabs and pages to show Recipes instead of Configs

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

requirements.txt

@@ -5,5 +5,7 @@ fastapi>=0.109.0
 uvicorn>=0.27.0
 python-multipart>=0.0.6
 PyYAML>=6.0
+asyncpg>=0.29.0
+ipfshttpclient>=0.8.0
 # Core artdag from GitHub
 git+https://github.com/gilesbradshaw/art-dag.git