Agent chip label is unclear and has no tooltip

[hamza-usmani]

Steps to reproduce

1. Open an agent pane.
2. Look at the agent chip.
3. Hover over it.

Expected Behavior

The chip communicates the agent's state in plain language, and hovering explains it further.

Actual Behavior

The current label does not make it clear what state it is describing, and there is no tooltip to fall back on.

Proposed fix

Reword around something concrete like "connected" or "linked", and add a tooltip. Whatever wording is chosen should match the terminology used elsewhere in the product.

Related: #518 Agent Pane UX umbrella.