Can't tell I cancelled session from chat sessions view

[bamurtaugh]

Related: #263348

I cancelled a coding agent session, and the status of the session moved from the blue in-progress indicator to the green completed indicator:

I would've expected a different indicator for a cancelled session.

[bamurtaugh]

My expectation for a different icon would also extend to the Copilot on My Behalf section of GHPR, which today also shows a green icon for a cancelled session, cc @alexr00:

[alexr00]

I think we need to get the session log for this at the moment, which seems expensive. I've asked if we can get canceled added to the events we already get through the API. Once we get that API, we can switch to using the red x Copilot icon for canceled.