The ecc@ecc plugin namespaces agents, commands and skills as `ecc:<name>`.
A manual install (install-apply --target claude|claude-project) places the
same files at bare names under ~/.claude, so plugin-prefixed references in
copied markdown point at agents and commands that do not exist in that
layout (e.g. subagent_type "ecc:planner", frontmatter agent: ecc:...).
- Add plugin-namespace.js with stripPluginNamespace(), which removes the
`ecc:` prefix before an identifier and leaves `ecc@ecc`, URLs and words
ending in "ecc" alone.
- Apply it to markdown copy operations when the target is claude or
claude-project. Non-markdown files and other targets are unchanged.
- Reword the agents rule so it describes both install modes instead of
stating that agents only ship with the plugin.
- Cover the transform with tests/lib/install-plugin-namespace.test.js.
