Fix expired calculation to be 6 months from now instead of setting to June

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/stores/login.test.js

@@ -143,4 +143,17 @@ describe('loginStore', () => {
     store.setIsLoggedIn(true);
     expect(store.isLoggedIn).toBe(true);
   });
+
+  describe('expired', () => {
+    it('is approximately 6 months in the future', () => {
+      const now = new Date();
+      const sixMonthsLater = new Date(now);
+      sixMonthsLater.setMonth(sixMonthsLater.getMonth() + 6);
+
+      const expiredDate = new Date(store.expired);
+      // Allow 1 day tolerance
+      const diffMs = Math.abs(expiredDate.getTime() - sixMonthsLater.getTime());
+      expect(diffMs).toBeLessThan(24 * 60 * 60 * 1000);
+    });
+  });
 });