Plugin MCP servers display inconsistently in /plugin list UI

Bug

When a plugin bundles multiple MCP servers via .mcp.json, the /plugin list UI shows inconsistent indentation — only the first MCP is displayed as a child of the plugin, the rest appear at the same level as independent plugins.

Steps to reproduce

1. Create a plugin with .mcp.json containing two MCP servers:

{
  "mcpServers": {
    "brave-search": { ... },
    "tavily-search": { ... }
  }
}

1. Install the plugin via marketplace
2. Run /plugin list

Expected

Both MCP servers should be indented under the plugin as children:

    smart-search Plugin · smart-search · ✔ enabled
    └ brave-search MCP · ✔ connected
    └ tavily-search MCP · ✔ connected
    superpowers Plugin · claude-plugins-official · ✔ enabled

Actual

Only the first MCP is shown as a child. The second appears at the top level:

    smart-search Plugin · smart-search · ✔ enabled
  ❯ └ brave-search MCP · ✔ connected
    tavily-search MCP · ✔ connected
    superpowers Plugin · claude-plugins-official · ✔ enabled

tavily-search has no indentation and appears to be a sibling of superpowers, not a child of smart-search.

Environment

• OS: Windows 11
• Claude Code version: latest
• Plugin: https://github.com/JiangHe12/smart-search

Impact

Visual only — both MCPs are functionally correct (tools work, hooks trigger). But the display is confusing for users trying to understand plugin component ownership.