Smooth account run chip motion

[yvette-carlisle]

Summary

• Animate native app account run summaries and run chips when lane assignments appear or disappear.
• Animate WebUI stable-list insertions and height changes so active-run rows do not pop in abruptly.
• Keep reduced-motion behavior explicit and add dashboard assertions for the animation hooks.

Validation

• cargo test -p decodex operator_dashboard
• swift test --package-path apps/decodex-app