fix: reject blank imported budget item names

src/export/json.test.ts

@@ -163,6 +163,23 @@ describe("import rejects invalid folder graph", () => {
     data.posts[0]!.order = 0;
     expect(() => parse(data)).toThrow(ImportValidationError);
   });
+
+  test("rejects a blank post name", () => {
+    const data = populated();
+    data.posts[0]!.name = "  ";
+    expect(() => parse(data)).toThrow(ImportValidationError);
+  });
+
+  test("rejects a blank recurring-cost name", () => {
+    const data = populated();
+    data.recurring.push({
+      id: "rent", name: "  ", order: 3, folderId: null, archived: false,
+      amount: { amount: 100, currency: "DKK" }, startDate: "2026-01",
+      recurrence: { kind: "everyNMonths", n: 1 }, anchoring: "calendar",
+      splitMode: "percent", splits: [{ postId: data.posts[0]!.id, value: 100, absorbsRemainder: true }],
+    });
+    expect(() => parse(data)).toThrow(ImportValidationError);
+  });
 });
 
 test("describeDataset counts what an import would replace", () => {