[MCP Apps] Add forgotten style variable

[martinalong]

Motivation and Context

• Adds a color variable token to the spec that was forgotten earlier
• Uses more of the style variables in customer-segmentation-server

How Has This Been Tested?

Manually tested

Breaking Changes

No

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/modelcontextprotocol/ext-apps/@modelcontextprotocol/ext-apps@174

commit: d797ed1

[antonpk1]

thanks!