Add component tests for presentational components and Login

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

tests/components/Loading.test.js

@@ -0,0 +1,16 @@
+import { describe, it, expect } from 'vitest';
+import { mount } from '@vue/test-utils';
+import Loading from '@/components/Loading.vue';
+
+describe('Loading', () => {
+  it('renders a loader element', () => {
+    const wrapper = mount(Loading);
+    expect(wrapper.find('.loader').exists()).toBe(true);
+  });
+
+  it('has full-screen overlay classes', () => {
+    const wrapper = mount(Loading);
+    expect(wrapper.classes()).toContain('fixed');
+    expect(wrapper.classes()).toContain('inset-0');
+  });
+});