Fleet view: session tabs, cloud list notices, and pinned or grouped cloud rows

What

The fleet view is the screen that lists your running sessions. The remote (cloud) part of it gets several changes:

• After you attach to a session and come back, the fleet view can move to the next session through sessionTabsNext instead of returning to the list, keeping track of which sessions were visited or have ended. This only runs when certain display conditions are met.
• When loading the remote session list fails, the previous remote rows now stay listed, the failure is recorded (remoteListFailure), and the screen can show a cloudListNotice. Before, the error was only logged. The log line starts [fleet:remote] list failed after.
• Cloud rows can now be grouped or pinned, and those marks are saved (readCloudRowMarks, saveCloudRowMarks).
• Refreshing the remote list (refreshRemote) is limited to once per second.
• Clicking a link now runs through new code that gathers context first.
• The simple view can be forced with CLAUDE_CODE_FLEETVIEW_SIMPLE.

This code sits behind the gates tengu_fleetview_simple, tengu_fleetview_peers and tengu_fleetview_pr_batch; nothing has been read about their state.

Why

Cloud sessions should stop vanishing from the list on brief errors, and you can organise them by grouping or pinning. Session tabs may let you move between sessions without going back to the list, though they may not be visible yet.