[plugins] Agent unavailable when installing plugins from marketplace

[PtitCaius]

When installing plugins from awesome-copilot (e.g. copilot plugin install awesome-copilot@awesome-copilot), the awesome-copilot agent is unavailable with the following error (on a ubuntu docker with GitHub Copilot CLI 0.0.412.) :

Failed to read agent directory "/root/.copilot/installed-plugins/awesome-copilot/awesome-copilot/agents/meta-agentic-project-scaffold.md": Error: ENOTDIR: not a directory, scandir 
 '/root/.copilot/installed-plugins/awesome-copilot/awesome-copilot/agents/meta-agentic-project-scaffold.md'

According to the plugin documentation of copilot CLI , the plugin.json should mention the root folder of agent files (here agents/).