Add external model persistence foundation

src/domain/ports/external-model-state.reader.ts

@@ -0,0 +1,10 @@
+import type { ExternalModelStateSnapshot } from "../../external-model/domain/external-model-contracts.js";
+
+export interface ExternalModelStateReadResult {
+  projectExists: boolean;
+  state: ExternalModelStateSnapshot;
+}
+
+export interface ExternalModelStateReader {
+  getByProject(projectId: string): ExternalModelStateReadResult;
+}