Persist Revit CSV configuration

tests/project-state-snapshot.test.ts

@@ -31,6 +31,7 @@ function minimalSnapshot() {
       ],
     },
     distributionBoards: [],
+    externalCsvConfiguration: null,
     circuitLists: [],
     circuitSections: [],
     distributionBoardComponents: [],
@@ -147,11 +148,24 @@ describe("project state snapshot model", () => {
     const baseline = structuredClone(minimalSnapshot());
     baseline.schemaVersion = 1 as typeof baseline.schemaVersion;
     delete (baseline.project as Record<string, unknown>).isPublicBuilding;
+    delete (baseline as Record<string, unknown>).externalCsvConfiguration;
 
     const upgraded = parseProjectStateSnapshot(baseline);
 
     assert.equal(upgraded.schemaVersion, projectStateSnapshotSchemaVersion);
     assert.equal(upgraded.project.isPublicBuilding, false);
+    assert.equal(upgraded.externalCsvConfiguration, null);
+  });
+
+  it("upgrades snapshot version 2 with an empty external CSV configuration", () => {
+    const previous = structuredClone(minimalSnapshot());
+    previous.schemaVersion = 2 as typeof previous.schemaVersion;
+    delete (previous as Record<string, unknown>).externalCsvConfiguration;
+
+    const upgraded = parseProjectStateSnapshot(previous);
+
+    assert.equal(upgraded.schemaVersion, projectStateSnapshotSchemaVersion);
+    assert.equal(upgraded.externalCsvConfiguration, null);
   });
 
   it("rejects malformed baseline and unknown snapshot shapes", () => {