feat(FN-1238): add dashboard loading screen with animated loader component

- Create DashboardLoader component with pulsing Fusion logo and progress bar animation
- Add CSS keyframe animations for smooth loading states
- Gate initial App render with loader until dashboard data is ready
- Add comprehensive tests for DashboardLoader component and App loading behavior
- Update existing App tests to account for loader wrapper

packages/dashboard/app/components/__tests__/App.test.tsx

@@ -1330,10 +1330,11 @@ describe("App footer-safe project layout", () => {
       expect(fetchSettings).toHaveBeenCalled();
     });
 
-    // Wrapper should have project-content but NOT project-content--with-footer
-    const wrapper = document.querySelector(".project-content");
-    expect(wrapper).toBeTruthy();
-    expect(wrapper?.classList.contains("project-content--with-footer")).toBe(false);
+    await waitFor(() => {
+      const wrapper = document.querySelector(".project-content");
+      expect(wrapper).toBeTruthy();
+      expect(wrapper?.classList.contains("project-content--with-footer")).toBe(false);
+    });
   });
 
   it("adds and removes footer class when switching between project and overview", async () => {