When PICARD_PLUGIN_REGISTRY_URL is set to a custom/local registry, CLI commands like install and browse still use the official registry data if its cache file exists on disk.
Steps to reproduce:
- Run picard-cli plugins browse (this caches the official registry)
- Set PICARD_PLUGIN_REGISTRY_URL=/path/to/local/registry.toml
- Run picard-cli plugins refresh-registry (succeeds, reports local file loaded)
- Run picard-cli plugins install my-local-plugin → "not found in registry"