feat: 清理示例数据并统一空态体验

frontend/src/store/auth.test.ts

@@ -39,7 +39,7 @@ describe("auth store logout", () => {
     const session = useSessionStore();
     const auth = useAuthStore();
 
-    session.lock("token_invalid", "demo@example.com", Date.now() + 60_000);
+    session.lock("token_invalid", "user@example.com", Date.now() + 60_000);
     auth.logout();
 
     expect(session.locked).toBe(false);

frontend/src/store/study.test.ts

@@ -46,8 +46,8 @@ describe("study store startup rehydration", () => {
       "ctms_current_study",
       JSON.stringify({
         id: "deleted-study",
-        code: "DEMO-CTMS",
-        name: "示例临床试验项目",
+        code: "ARCHIVED-CTMS",
+        name: "已删除项目",
       })
     );
     fetchStudies.mockResolvedValue({