Feature request: per-project MCP server opt-out (deny list)

Currently, MCP servers configured globally are loaded for every project, with no way to suppress them per-repo. This has a real token cost — every connected server's tool definitions are injected into context on each request.

Request: support a project-level MCP deny list (e.g. in .mcp.json) so that globally configured servers can be excluded for specific projects.

Example:

{
  "disabled": ["claude.ai Gmail", "claude.ai Google Calendar", "claude.ai Google Drive"]
}

This would let teams keep personal integrations (Gmail, Calendar) globally configured while keeping project contexts lean and cost-efficient.