Dev Portal: Migrate your Dev Portal appearance how to

## Jobs to be done (optional)

## Definition of done
Use this demo for reference: https://konghq.zoom.us/clips/share/U_QnHKPITXGk_uafTr1gfA

Create a new how to that uses the [VS code extension](https://marketplace.visualstudio.com/items?itemName=konghq.vscode-konnect-dev-portal-toolkit), various [Dev Portal skills](https://developer.konghq.com/skills/), and the Konnect MCP server with the story that we're showing a user how they can quickly migrate their appearance customization of their current portal to Dev Portal.

## Information
Request: https://kongstrong.slack.com/archives/CDSTDSG9J/p1785434469576819

## Due date (optional)

## Size

Start with the linked demo, VS Code extension, Dev Portal skills, and Konnect MCP server documentation to understand the intended migration story. Done means a new how-to is published showing users how to migrate their existing portal appearance customization to Dev Portal using these tools.

Written by the indexing model from the issue text.