Automations: add Archive action to hover actions of an automation history entry

[copilot-swe-agent]

Description

Each run listed in the Automations history (AutomationHistorySection in src/vs/sessions/contrib/sessions/browser/views/automationsView.ts) shows a hover toolbar (Menus.AutomationsHistoryItem) with Stop and Delete actions, registered in registerAutomationHistoryItemActions():

function registerAutomationHistoryItemActions(): IDisposable {
	return combinedDisposable(
		MenuRegistry.appendMenuItem(Menus.AutomationsHistoryItem, {
			command: { id: STOP_AUTOMATION_RUN_SESSION_COMMAND_ID, title: "Stop", icon: Codicon.stopCircle },
			...
		}),
		MenuRegistry.appendMenuItem(Menus.AutomationsHistoryItem, {
			command: { id: DELETE_AUTOMATION_RUN_SESSION_COMMAND_ID, title: "Delete", icon: Codicon.trash },
			...
		}),
	);
}

There is no way to archive the session behind a history entry directly from the list. Today the only way to archive a session is to open it and use the archive control in the session's own header, there's no quick action from the history row itself.

Suggested fix

Add an Archive action (calling sessionsManagementService.archiveSession(session), mirroring the existing Stop/Delete handling in handleSessionToolbarAction) to the Menus.AutomationsHistoryItem hover toolbar, gated by an appropriate when clause (e.g. not already archived, session created) similar to the existing SessionIsArchivedContext usage in sessionsActions.ts.

Context

Raised internally:

rob: How do automation sessions get archived, to clean up the worktree? Seems like they can only be deleted
Ben Villalobos: currently you can only delete from the view directly. A quick way to do it would be to click into the session itself and click archive from the controls at the top