All IPFS operations now use IPFS_API (multiaddr format) instead of
separate IPFS_GATEWAY config. This fixes effect loading in Docker where
the gateway URL defaulted to localhost.
- Add tests for effect loading and IPFS configuration
- Simplify docker-compose.yml (remove IPFS_GATEWAY)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>