[Good First Issue] Add useful empty states to all Glass modes

[Gupta91]

Problem

Some Glass modes have sparse or inconsistent empty states.

Expected Behavior

Add helpful empty states to Scratch, Automations, Memory, Pending, and Connected.

Acceptance Criteria

• Empty states explain what the surface is for.
• Empty states suggest one useful next action when appropriate.
• Copy is concise and consistent with the rest of Glass.