* fix(app): stabilize streamed chat rendering
Use deterministic Markdown AST keys and preserve unique row identities when an assistant message resumes after a tool. Keep native gesture and plan-card children correctly keyed to avoid unsupported Fabric reconciliation paths.
* fix(app): stabilize retained native panels
Keep retained workspace roots in a stable native order and make active
panels present in the selection commit. Hidden panels now stop expensive
subscriptions and animations without losing mounted state.
* fix(app): harden retained panel activity
