- ModelStore/FileVault: drop nonisolated(unsafe) on shared, mark all instance
methods nonisolated (they only read filesystem); ModelKind enum also nonisolated
- AIRuntime ↔ ModelStore cross-actor call resolved by the above
- LLMSession: replace deprecated Device.setDefault(device:) with task-scoped
Device.withDefaultDevice(.cpu, body:); wrap both load and generate so the
TaskLocal propagates through ModelContainer.perform