Refresh the chat screenshot, and the prose the UI change invalidated

[github-actions]

Refreshes the mock-backed chat screenshots and fixes the prose they broke.

What changed in the UI

kagent-dev/kagent#2847 (Sept 17) renamed the chat's checkpoint to Snapshot, gave it a generated name, and moved Fork, Rename and Delete onto the snapshot's mark. The old Checkpoint / Fork / Remove strip is gone.

The baseline this replaces was captured Sept 15, so it predates that change. #522 refreshed only the Substrate pair, which is why this went unnoticed for eight days.

Prose fixed in observability/launch-ui.md

• Both alt texts promised "a tool call and a checkpoint". The new card is taller than the strip it replaced and pushes the tool call out of the transcript's scroll container, so neither is in frame.
• "Two controls under the transcript" described Checkpoint and Fork. There are now three, and they sit on the snapshot's mark.
• Added what Rename and Delete do, and how a checkpoint is taken now that the control is an icon beside the composer.

The terminology collision

The UI's "Snapshot" is not the glossary's Snapshot. In Agent Substrate a snapshot is the state an Actor suspends to; a checkpoint pins one. The UI now applies the word snapshot to the pin. The section states that mapping explicitly and keeps the concept named checkpoint throughout, so looking the UI label up in the glossary does not land on the wrong object. Delete is described as releasing the pin, matching substrate-runtime/suspend-and-resume.md, rather than paraphrasing the button tooltip.

Other pages that mention checkpoints were checked and are unaffected — they describe the gRPC API and the runtime, where the name has not changed.

Notes for the reviewer

• The images are also a one-time rebaseline onto the CI renderer. Every prior baseline was captured locally on macOS; this is the first capture on an ubuntu runner, so text metrics shift by a pixel or two independently of the UI change.
• The snapshot name in the capture is the generated <agentInstanceId>-<headTaskId>, which reads as a raw UUID. Making it friendlier means naming it in the mock fixture, which lives in the kagent repo.
• Restoring the tool call to the frame needs the spec to scroll the transcript container; fullPage does not reach it. Recorded in chat.spec.ts, not attempted here.
• Merge rather than leave open. create-pull-request force-pushes this branch, so the next workflow run would discard the two prose commits.

Generated by the Refresh kagent UI screenshots workflow; prose commits added by hand.

[github-actions]

Docs preview

Link	Points at
Branch preview	The newest push to this branch. Updates in place.
Commit preview	e464d3c only. Frozen.

Both are uploaded Worker versions and serve no production traffic.