Allow for configuring marketplaces or individual plugins.
Both are provided as a list of either paths or packages.
The lone plugins are enabled by adding a --plugin-dir argument to the wrapper script.
Marketplaces are saved to the nix store and enabled by adding to the claude settings and known_marketplaces files.
With the marketplace "installed", the plugin can just be enabled via the enabledPlugins setting.
Add `enableMcpIntegration` option to merge MCP servers from
`programs.mcp.servers` into Claude Code configuration. Claude Code
servers take precedence over general MCP servers when both define
the same server name.
