Refine desktop lane popover

[yvette-carlisle]

Summary:

• Redesign the desktop lane pill popover to be more compact and aligned without duplicating pill-level identity.
• Stabilize desktop run-activity snapshot handling so transient socket gaps or empty activity events do not hide Running/pill UI.

Verification:

• swift test --package-path apps/decodex-app --filter AccountModelTests
• swift test --package-path apps/decodex-app
• cargo make test-decodex-app-stage
• git diff --check