Add Loading Indicator with isWaiting()

This skill adds loading state tracking to widgets using context.isWaiting().

What This Skill Does

Shows loading indicators in widgets by:

• Using context.isWaiting(key) to check if an operation is in progress
• Displaying appropriate loading UI (spinner, skeleton, overlay)
• Automatically updating when the operation completes

Instructions

Step 1: Ensure Cubit Uses mix()

The Cubit method must use mix() with a key: