Subtle Cloud badge for Cloud workspaces in left sidebar

[austinywang]

Problem

Cloud-backed workspaces are difficult to distinguish from local workspaces in the left sidebar. A user should be able to identify a Cloud workspace at a glance without opening the Machines panel or relying on a title convention.

Request

Add a restrained Cloud badge to Cloud-backed workspace rows in the left sidebar. It should be visible enough to scan quickly, but must not dominate the row or compete with workspace names.

Expected behavior

• Cloud rows show a compact cloud symbol and/or Cloud badge in the existing sidebar status/accessory area.
• The badge uses the existing cmux visual language and works in light/dark themes.
• The workspace name remains primary; the badge is secondary and low contrast when inactive.
• VoiceOver/accessibility exposes a clear label such as Cloud workspace on <machine>; color or icon alone is insufficient.
• The marker comes from authoritative Cloud workspace metadata/binding, never from parsing titles or paths.
• The distinction survives app restart, reconnect, sleeping machines, and similar names for local and Cloud workspaces.
• Narrow sidebars truncate gracefully without hiding the workspace name or producing layout churn.
• Existing local workspace rows, drag/reorder behavior, keyboard navigation, and selection remain unchanged.

Verification

Add behavior-level coverage for local-vs-Cloud rows with similar names and for reconnect/session restoration. Add focused UI evidence or an isolated dogfood build showing light/dark and narrow-sidebar states. Do not add a new sidebar section or a large persistent machine dashboard for this issue.