disabled: true flag in mcpServers should set default state for new projects

Current Behavior

When configuring MCP servers in ~/.claude.json with disabled: true:

"mcpServers": {
  "awslabs.ccapi-mcp-server": {
    "command": "uvx",
    "args": ["awslabs.ccapi-mcp-server@latest"],
    "disabled": true
  }
}

New projects initialize with an empty disabledMcpServers array, which causes all MCPs to be enabled regardless of the global disabled flag.

Expected Behavior

The disabled: true flag should set the default state for new projects. MCPs marked as disabled should start disabled in new projects, but users should still be able to enable them per-project via /mcp.

Workaround Attempted

• managed-settings.json with deniedMcpServers works but is an absolute block - MCPs cannot be re-enabled per-project
• Manually disabling via /mcp for each new project works but is tedious

Suggested Implementation

When creating a new project entry, populate disabledMcpServers based on the disabled: true flags in the global mcpServers config.