[FEATURE] Add /colour as an alias for /color"

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

It's a common British/international spelling variant and should be cheap to add

Proposed Solution

/colour will be an alias for /color

Alternative Solutions

New

Priority

Low - Nice to have

Feature Category

CLI commands and flags

Use Case Example

self evident

Additional Context

_No response_