chore: establish YCode replication baseline and TODO

src/shared/assistant-model.ts

@@ -0,0 +1,6 @@
+import type { CustomModelProfile } from './models'
+
+/** Freeze the selected profile's identity before a turn can outlive its settings. */
+export function freezeAssistantModelMetadata(model: Pick<CustomModelProfile, 'id' | 'name'>): { modelId: string; modelName: string } {
+  return { modelId: model.id, modelName: model.name }
+}